ither L, the common iliac, V, the external iliac, or the internal iliac
vessel, were the subject of the operation by ligature.

DESCRIPTION OF PLATE 25.

A. The arch of the aorta.

B B. The descending thoracic part of the aorta, giving off b b, the
intercostal arteries.

C. The abdominal part of the aorta.

D D. First pair of ribs.

E. The xyphoid cartilage.

G G*. The right and left kidneys.

H. The brachio-cephalic artery.

I. Left common carotid artery.

K. Left subclavian artery.

L. Right common iliac artery at its place of division.

M. Left common iliac artery, seen through the meso-rectum.

N. Inferior vena cava.

O O. The sigmoid flexure of the colon.

P. The rectum.

Q. The urinary bladder.

R. The right iliac fossa.

S S. The right and left ureters.

T. The left common iliac vein, joining the right under the right common
iliac artery to form the inferior vena cava.

U. Fifth lumbar vertebra.

V. The external iliac artery of right side.

W. The symphysis pubis.

X. An incision made over the locality of the femoral artery.

b b. The dorsal intercostal arteries.

c. The coeliac axis

d. The superior mesenteric artery.

f f. The renal arteries.

g. The inferior mesenteric artery.

h. The vas deferens bending over the epigastric artery and the os pubis,
after having passed through the internal abdominal ring.

[Illustration: Chest and abdomen, showing bones, blood vessels, muscles
and other internal organs.]
Plate 25

COMMENTARY ON PLATE 26.

THE RELATION OF THE INTERNAL PARTS
TO THE EXTERNAL SURFACE OF THE BODY.

An exact acquaintance with the normal character of the external form,
its natural prominences and depressions, produced by the projecting
swell of muscles and points of bone, &c., is of great practical
importance to the surgeon. These several marks described on the
superficies he takes as certain guides to the precise locality and
relations of the more deeply situated organs. And as, by dissection,
Nature reveals to him the fact that she holds constant to these
relations, so, at least, may all that department of practice which he
bases upon this anatomical certainty be accounted as rooted in truth and
governed by fixed principles. The same organ bears the same special and
general relations in all bodies, not only of the human, but of all other
species of vertebrata; and from this evidence we conclude that the same
marks on surface indica