ady
descended through this aperture into the scrotum, and the testicle
follows it.

The descent of the testis is effected by a very slow and gradual process
of change. (Tout va par degres dans la nature, et rien par
sauts.--Bonnet.) But how, or by what distinct and active structural
agent, this descent is effected, or whether there does exist, in fact,
any such agent as that which anatomists name "gubernaculum testis," are
questions which appear to me by no means settled.[Footnote]

[Footnote: Dr. Carpenter (Principles of Human Physiology) remarks, that
"the cause of this descent is not very clear. It can scarcely be due
merely, as some have supposed, to the contraction of the gubernaculum,
since that does not contain any fibrous structure until after the
lowering of the testis has commenced." Dr. Sharpey (Quain's Anatomy, 5th
edition) observes, that "the office of the gubernaculum is yet
imperfectly understood." The opinions of these two distinguished
physiologists will doubtless be regarded as an impartial estimate of the
results of the researches prosecuted in reference to these questions by
Haller, Camper, Hunter, Arnaud, Lobstein, Meckel, Paletta, Wrisberg,
Vicq d'Azyr, Brugnone, Tumiati, Seiler, Girardi, Cooper, Bell, Weber,
Carus, Cloquet, Curling, and others. From my own observations, I am led
to believe that no such muscular structure as a gubernaculum exists, and
therefore that the descent of the testis is the effect of another cause.
Leaving these matters, however, to the consideration of the
physiologist, it is sufficient for the surgeon to know that the testis
in its transition derives certain coverings from the parietes of the
groin, and that a communication is thereby established between the
scrotal and abdominal cavities. ]

The general lining membrane of the foetal abdomen is composed of two
layers--an outer one of fibrous, and an inner one of serous structure.
Of these two layers, the abdominal viscera form for themselves a double
envelope. [Footnote] The testis in the loins has a covering from both
membranes, and is still found to be enclosed by both, even when it has
descended to the scrotum. The two coverings of fibro-serous structure
which surrounded the testis in the loins become respectively the tunica
albuginea and tunica vaginalis when the gland occupies the scrotal
cavity.

[Footnote: Langenbeck describes the peritonaeum as consisting of two
layers; one external and fibrous, another int