PLATE 37.

All the letters except the following indicate the same parts as in Plate
35.

F. The epigastric artery passing between the two hernial sacs

G. The umbilical ligament.

H. The neck of the sac of the external hernia.

I. The neck of the sac of the internal hernia.

[Illustration: Abdomen, showing blood vessels, muscles
and other internal organs.]
Plate 37

PLATE 38.--AN ANTERIOR VIEW OF PLATE 37.

All the letters, with the exception of the following, refer to the same
parts as in Plate 36.

G. The funnel-shaped elongation of the fascia transversalis receiving g,
the sac of the external bubonocele.

H. The sac of the internal inguinal hernia invested by h, the
transversalis fascia.

Q. The spermatic vessels lying on the outer side of H, the direct
inguinal hernia.

[Illustration: Abdomen and leg, showing blood vessels, muscles
and other internal organs.]
Plate 38

COMMENTARY ON PLATES 39 & 40.

DEMONSTRATIONS OF THE NATURE OF CONGENITAL AND
INFANTILE INGUINAL HERNIAE, AND OF HYDROCELE.

PLATE 39. Fig. 1--The descent of the testicle from the loins to the
scrotum.--The foetal abdomen and scrotum form one general cavity, and
are composed of parts which are structurally identical. The cutaneous,
fascial, muscular, and membranous layers of the abdominal parietes are
continued into those of the scrotum. At the fifth month of foetal life,
the testicle, 3, is situated in the loins beneath the kidney, 2. The
testicle is then numbered amongst the abdominal viscera, and, like
these, it is developed external to the peritonaeal membrane, which forms
an envelope for it. At the back and sides of the testicle, where the
peritonaeum is reflected from it, a small membranous fold or mesentery
(mesorchium, Seiler) is formed, and between the layers of this the
nerves and vessels enter the organ, the nerves being derived from the
neighbouring sympathetic ganglia (aortic plexus), while the arteries and
veins spring directly from the main abdominal bloodvessels. It being
predetermined that the testicle, 3, should migrate from the loins to the
scrotum, 6 a, 7, at a period included between the sixth and ninth month,
certain structural changes are at this time already effected for its
sure and easy passage. By the time that the testis, 5, is about to enter
the internal inguinal ring, 6 a, (seventh or eighth month,) a process or
pouch of the peritonaeal membrane (processus vaginalis) has alre