304. ESSAYS 4nD OBSERVATIONS 
non-exiftence of air in this place. Such 
are the following. 
1. DissEcT the teguments and inter- 
coftal mufcles from the p/ezra of either a 
dead man or quadruped without wound- 
img this membrane, in which there is no 
difficulty ; then pull up and deprefs alter- 
nately the /fernum and ribs as often as you 
will, the lungs are feen contiguous all the 
while to the pleura; but, on making a 
fmall puncture ‘through this membrane, 
the lungs, if they are not grown to the 
pleura, which is often the cafe in the, hu- 
man fubject, fly from the pleura, and are 
no more feen. 
2, THIs connection ‘of the Lin and 
pleura, more or lefs of which is {een in 
moft human bodies, implies ftrongly a 
natural contiguity of thefetwo parts. 
Lay bare the pleura, without wounding 
it, between two ribs of any living qua- 
druped, which requires no great) dexter1- 
ty; and then the contiguity of the lungs — 
and. pleura may be feen, though the lungs ~ 
are conftantly fliding and changing place 
along 
