33 
elasticity of the lungs. 
living and sound state of the parts, the form of a cone, of 
which the apex looks towards the chest. 
The form of the diaphragm, or base of the chest, may be 
illustrated by the comparison of a wine bottle; the bottom of 
which is convex inwardly and concave outwardly ; the dia- 
phragm bearing in form and position the same relation to the 
chest, which the bottom does to the rest of the bottle. 
The cavity above the diaphragm is chiefly filled by the 
lungs, which therefore in the living system occupy a space 
nearly as large as the shell of the chest. 
As soon, however, as the chest has been opened, and the 
external surface of the lungs exposed to the contact of the 
circumambient air, these organs shrink into dimensions far 
less extensive than those which they occupy in the living 
body. 
The causes of the lungs being expanded in life into larger 
dimensions than those which are natural to them, or which 
they occupy when they have been extracted from the body, 
are curious and important, and may be thus explained. 
The walls or boundaries of the chest are well secured. 
They are at several places indeed perforated by tubes, but 
these tubes, at the place of their entrance or exit, are, as has 
been described, always securely concreted by an union of 
membranes with the substance of the chest. The chief of 
these perforations are made by the windpipe, the gullet, and 
some large blood vessels at the top; and at the bottom, by the 
gullet again in its passage out of the chest, the great de- 
scending aorta, and the inferior cava. Conceive then, the 
lungs to be placed in this cavity in such a manner that the 
windpipe should pass out of it at the top, having its exterior 
MDCCCXX. F 
