illae enim sunt, quae naturam uniunt, et constituere scientias
incipiunt." "Natura enim non nisi parendo vincitur; et quod in
contemplatione instar causae est; id in operatione instar regulae est."
(Novum Organum Scientiarum, Aph. xxvii-iii, lib. i.)]

The difference between the perpendicular range of the anterior and
posterior walls of the thoracic cavity may be estimated on a reference
to Plate 25, in which the xyphoid cartilage, E, joined to the seventh
pair of ribs, bounds its anterior wall below, while F, the pillars of
the diaphragm, bound its posterior wall. The thoracic cavity is
therefore considerably deeper in its posterior than in its anterior
wall; and this occasions a difference of an opposite kind in the
anterior and posterior walls of the abdomen; for while the abdomen
ranges perpendicularly from E to W, its posterior range measures only
from F to the ventra of the iliac bones, R. The arching form of the
diaphragm, and the lower level which the pubic symphysis occupies
compared with that of the cristae of the iliac bones, occasion this
difference in the measure of both the thorax and abdomen.

The usual position of the kidneys, G G*, is on either side of the lumbar
spine, between the last ribs and the cristae of the iliac bones. The
kidneys lie on the fore part of the quadratus lumborum and psoae
muscles. They are sometimes found to have descended as low as the iliac
fossae, R, in consequence of pressure, occasioned by an enlarged liver
on the right, or by an enlarged spleen on the left. The length of the
abdominal part of the aorta may be estimated as being a third of the
entire vessel, measured from the top of its arch to its point of
bifurcation. So many and such large vessels arise from the abdominal
part of the aorta, and these are set so closely to each other, that it
must in all cases be very difficult to choose a proper locality whereat
to apply a ligature on this region of the vessel. If other circumstances
could fairly justify such an operation, the anatomist believes that the
circulation might be maintained through the anastomosis of the internal
mammary and intercostal arteries with the epigastric; the branches of
the superior mesenteric with those of the inferior; and the branches of
this latter with the perineal branches of the pubic. The lumbar, the
gluteal, and the circumflex ilii arteries, also communicate around the
hip-bone. The same vessels would serve to carryon the circulation if
e