a hernia now occur, it cannot enter the tunica
vaginalis, and come into actual contact with the testicle. The hernia,
13, therefore, when about to force the peritonaeum, 6 a, near the closed
ring, 6 b, takes a distinct sac or investment from this membrane. This
hernial sac, 6 e, will vary as to its position in regard to the tunica
vaginalis, 6 d, according to the place whereat it dilates the
peritonaeum at the ring. The peculiarity of this hernia, as
distinguished from the congenital form, is owing to the scrotum
containing two sacs,--the tunica vaginalis and the proper sac of the
hernia; whereas, in the congenital variety, the tunica vaginalis itself
becomes the hernial sac by a direct reception of the naked intestine. If
in infantile hernia a hydrocele should form in the tunica vaginalis, the
fluid will also distend the pervious serous spermatic tube, 6 c, as far
up as the closed internal ring, 6 b, and will thus invest and obscure
the descending herniary sac, 13. This form of hernia is named infantile
(Hey), owing to the congenital defect in that process, whereby the
serous tube lining the cord is normally obliterated. Such a form of
hernia may occur at the adult age for the first time, but it is still
the consequence of original default.

[Illustration: Abdomen and scrotum, showing bone, blood vessels
and other internal organs.]
Plate 40--Figure 5.

PLATE 40, Fig. 6.--Oblique inguinal hernia in the adult.--This variety
of hernia occurs not in consequence of any congenital defect, except
inasmuch as the natural weakness of the inguinal wall opposite the
internal ring may be attributed to this cause. The serous spermatic tube
has been normally obliterated for its whole length between the internal
ring and the tunica vaginalis; but the fibrous tube, or spermatic
fascia, is open at the internal ring where it joins the transversalis
fascia, and remains pervious as far down as the testicle. The intestine,
13, forces and distends the upper end of the closed serous tube; and as
this is now wholly obliterated, the herniary sac, 6 c, derived anew from
the inguinal peritonaeum, enters the fibrous tube, or sheath of the
cord, and descends it as far as the tunica vaginalis, 6 d, but does not
enter this sac, as it is already closed. When we compare this hernia,
Fig. 6, Plate 40, with the infantile variety, Fig. 5, Plate 40, we find
that they agree in so far as the intestinal sac is distinct from the
tunica vaginalis; where