PHYSIOLOGY. 
Siicli attraction the cause of absorption, that 
process should be carried on with regulari- 
ty. On the contrary, absorption is occa- 
sionally very deficient, when abundance of 
fluids is presented to tlie mouths of the 
vessels, as in oedema ; and in other cases, 
after being for a long time inactive, it is 
suddenly exerted to a great extent ; thus 
large abscesses have been dispersed in one 
night. Others have endeavoured to dis- 
cover some propelling power which should 
protrude the matter sulqect to absorption 
into the mouths of the vessels. The pres- 
sure of the atmosphere on the surface of the 
body has been considered adequate to this 
effect, and the deposition of new matter by 
the secerning artery has been assigned as 
the cause of the propulsion of the old parti- 
cles into the orifice of the absorbent. On 
this theory, secretion and absorption should 
correspond inore exactly than they are 
known to do. Mr. J. Hunter acknowledged 
that he was unable to account for the ef- 
fects produced, unless by attributing to the 
mouths of the absorbing vessels powers si- 
milar to those which a caterpillar exerts 
when feeding on a leaf. 
Some suppose tliat the absorbents cannot 
take up any matter that is not fluid ; con- 
' sequently that animal solids must be con- 
verted into fluids before they can become 
fit subjects for absorption ; and that proba- 
bly some solvent fluid is secreted for this 
purpose. The latter fact rests on no direct 
proof, and the whole hypothesis is very un- 
like the simplicity observable in other parts 
of the animal economy. It seems better, 
in these difficult investigations, to note facts 
than to form theories ; and whoever con- 
templates the things done in the animal 
body, will be astonished at the power of 
the vessels, by whose agency they must be 
effected ; a whole bone may perish, as, for 
example, that of the thigh, and may be 
increased by a new one ; the vascular 
fining of the new bone will altogether re- 
move the dead one. 
Besides the great and leading office of 
the absorbents in conveying the chyle into 
the venous system, their agency is discerned 
in various other parts of the animal econo- 
my. The nearly transparent fluid that lu- 
bricates the interstices of the cellular sub- 
stance, and the serous exhalation poured 
into circumscribed cavities, are taken up 
by the lymphatics, which must commence 
in all parts of the body by open orifices. 
When the due balance does not exist be- 
tween the absorbing and secreting vessels, 
the cellular substance becomes loaded wifli 
fluid (anasarca), or circumscribed cavities 
are rendered dropsical. Together with the 
lymph or fluid which the absorbing vessels 
derive from the sourcesjust-mentioned, they 
convey from every part of the body the old 
constituent materials of our organs in pro- 
portion as new particles are deposited by 
the arteries ; and these different elements 
are intimately mingled and combined in 
their passage through the absorbent glands, 
and the plexures of lymphatic vessels. 
It has been a disputed point whether ab- 
sorption goes on from the surface of the 
skin, while the cuticle is entire ; the argu- 
ments on the affirmative sides are an alleged 
increase of weight in the body after a walk 
in damp weather ; the abundant secretion 
of urine after remaining for some time in a 
bath ; the evident swelling of the inguinal 
glands after a long immersion of the lower 
extremities in warm water ; the effects of 
mercury administered by friction, fumiga- 
tion, &c. It has been stated in opposition, 
that oil of turpentine has not been absorbed 
after long immersion of the arm ; that so- 
lutions of medicated substances have not 
been taken up under similar circumstances, 
&c. We think it is sufficiently proved, 
that absorption from the surface does take 
place in the human body, but whether this 
extends, as a modern physiologist has 
stated, to gaseous bodies, cannot yet be de- 
cided. 
It appears probable that the internal sur- 
face of the bronchi and pulmonary vesicles 
is an absorbing surface. For when a per- 
son breathes air loaded with the vapour of 
turpentine, that substance very speedily 
shews itself in the urine; although the skui 
will not take it up. If the body really 
increase in weight in damp air, it might 
be accounted for by means of pulmonary 
absorption. It must probably be rather 
in this way, or by the skin, that contagions 
matters affect the constitution. 
The absorbents are concerned in pro- 
ducing changes in the different secreted 
fluids : they remove the aqueous portions of 
the bile and urine, and often take up even 
the colouring parts of the former, and con- 
vey them into the blood, whence they are 
deposited in all our organs, and produce the 
yellowness of jaundice. They introduce 
various diseases into the human frame, as 
syphilis, hydrophobia, inoculated small-pox, 
&c. ; and in other instances act in a cura- 
tive manner by taking up extravasated 
blood, by reducing swollen parts, &c. 
