ing these vessels in several situations.
Practical observations on wounds of the arteries of the leg and foot.

CONCLUDING COMMENTARY

ON THE FORM AND DISTRIBUTION OF THE VASCULAR SYSTEM AS A
WHOLE; ANOMALIES; RAMIFICATION; ANASTOMOSIS.

The double heart. Universal systemic capillary anastomosis. Its
division, by the median line, into two great lateral fields--those
subdivided into two systems or provinces--viz., pulmonary and systemic.
Relation of pulmonary and systemic circulating vessels. Motions of the
heart. Circulation of the blood through the lungs and system. Symmetry
of the hearts and their vessels. Development of the heart and primary
vessels. Their stages of metamorphosis simulating the permanent
conditions of the parts in lower animals. The primitive branchial arches
undergoing metamorphosis. Completion of these changes. Interpretation of
the varieties of form in the heart and primary vessels. Signification of
their normal condition. The portal system no exception to the law of
vascular symmetry. Signification of the portal system. The liver and
spleen as homologous organs,--as parts of the same whole quantity.
Cardiac anastomosing vessels. Vasa vasorum. Anastomosing branches of the
systemic aorta considered in reference to the operations of arresting by
ligature the direct circulation through the arteries of the head, neck,
upper limbs, pelvis, and lower limbs. The collateral circulation.
Practical observations on the most eligible situations for tying each of
the principal vessels, as determined by the greatest number of their
anastomosing branches on either side of the ligature, and the largest
amount of the collateral circulation that may be thereby carried on for
the support of distal parts.

[End Table of Contents]

COMMENTARY ON PLATES 1 & 2.

THE FORM OF THE THORACIC CAVITY, AND THE POSITION OF THE LUNGS,
HEART, AND LARGER BLOODVESSELS.

In the human body there does not exist any such space as cavity,
properly so called. Every space is occupied by its contents. The
thoracic space is completely filled by its viscera, which, in mass, take
a perfect cast or model of its interior. The thoracic viscera lie so
closely to one another, that they respectively influence the form and
dimensions of each other. That space which the lungs do not occupy is
filled by the heart, &c., and vice versa. The thoracic apparatus causes
no vacuum by the acts of either contraction or dilatation. Neither do
the