Magendie on Absorption. 299 
duced therefrom, I should even then, only have ex- 
plamed the absorption of substances which are soluble 
in our humours; gases and vapours cannot be submit- 
ted to capillary attraction, and yet, every one knows that 
these bodies are absorbed, and that often, with great rapidi- 
ty. An animal plunged into sulphuretted hydrogen gas, 
and immediately withdrawn, is often struck with death. 
have seen rabbits die fron a single inspiration of prussic va~ 
pour. How can these phenomena be explained? - 
To understand them, we must remember that the mem- 
branes of animals seem to offer but a feeble resistance to 
the free circulation of the gases and vapours. Blood con- 
tained in a bladder, reddens at its surface as though it were 
in immediate contact with oxygen gas; pure hydrogen gas, 
facts in which - living membranes conduct in the same 
manner. ‘The venous blood reddens in the lungs, when it is 
separated from jen air only by the vascular membrane ; the 
same effect is produced in the gills of fishes. The b eauti- 
ful experiments of Mr. Edwards have recently proved that 
the skins of eartpin: reptiles offer-A psborhoten: —_ 
alagous. 
-Thave inepaetl lately stemedk that, ia birds and yours 
miferous. animals, the blood modditean, and assumes the arte- 
rial qualities, in the jugular vein when uncovered and ex- 
posed to the air, if the precaution be taken to slacken the 
circulation by a slight pressure on the lower extremity (ex- 
trémité cardiaque) of the vein. 
It appears, therefore that the absorption of the gases and 
vapours, should be attributed to the assetaitore of the li 
ing membranes to those bodies. The theory 0 f that per- 
eability i is not yet ell ding the ef- 
for brat Spueet as Priestly and Dalton ; 
but here- physiology seas stop, and depend for its future 
pecenny es. af, 55 shea scienee: ; 
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