PHYSIOLOGY. 
inflammation, which is an increased action 
of parts, raises organic into animal sensibi- 
lity in diseases of bones, &c. 
Diiferent stimuli, applied to the same or- 
gan, determine the developenient of one 
or other of these powers : thus no sen- 
sation is transmitted to the brain from 
the passage of blood in the arteries, but 
when an extraneous fluid is injected, the 
animal’s cries shew that he feels it. The 
coats of the stomach experience in the 
healthy state no perceptible impression 
from the food, but very distinct and even 
painful sensations are transmitted to the 
brain when a few grains of poisonous mat- 
ter are mingled with the aliment. The 
animal sensibility excited on mucous mem- 
branes by foreign bodies (as bougies in the 
urethra, &c.) is quickly lost, and subsides 
■into organic. 
Each organ seems to have, independently 
of accidental variations, an original quan- 
tity or dose of sensibility, to which it re- 
turns after any deviation. In this consists 
the peculiar life of each organ, and from 
this arise the relations which it has to ex- 
traneous substances. Hence excretory 
ducts, opening on mucous membranes, .re- 
fuse admission to the substances passing 
along those canals. Hence the lacteals ab- 
sorb the chyle only. These particular re- 
lations may also take place with matters 
foreign to the body, as welt as with animal 
fluids, as we see in the case of medicines 
acting on particular organs, as cantharides, 
mercury, &c. 
Contraction is the common, but not the 
universal mode of animal motions. For the 
iris, corpus cavernosum, Sic. dilate when 
they move. Organic contractility is always 
and immediately connected with organic 
sensibility, for there is no intermediate 
function between these ; the organ itself is 
the point in which the sensation ends, and 
from which the principle of contraction be- 
gins, The animal sensibility and contrac- 
tility are not so closely united , we may feel 
without moving : here the nerves and brain 
perform their functions between the action 
of the two powers. 
Sensible organic, or, in other words, in- 
voluntary and sensible contractility, cor- 
responds very nearly to irritability ; while 
the insensible seems more like tenacity. 
To consider irritability as the exclusive 
endowment of muscles, is taking a very 
contracted view of the subject. These or- 
gans have indeed the largest portion, but 
«verypart possessing life reacts, although 
less manifestly, on the application of cer- 
tain stimuli. No rule is more fallacious 
than that of estimating the muscularity of a 
part by the action of artificial irritants. 
The organic and animal contractilities can- 
not be converted into each other as the cor- 
responding sensibilities can. 
The parts of the living body possess also 
some powers which result merely from their 
organization, and have been denoted by 
physiologists under the epithet of vis mor- 
tua. Thus they admit of extension beyond 
the natural state from extraneous impulse, 
and of contraction when that impulse ceases 
to operate. This extensility and contrac- 
tility are independent of life, and are ter- 
minated only by death. ■ The stretchiug of 
muscles by moving a limb, the extension of 
the skin over a tumour, its retraction when 
divided, &c. are examples of these powers. 
They have been confounded by some puy- 
siologists with the insensible organic con- 
tractility. 
A muscle exhibits all the powers now 
enumerated. It contracts, in obedience to 
the will, by its animal contractility ; from 
the application of stimuli, by its organic 
sensible contractility. Its nutrition and 
growtli show the existence of organic insen- 
sible contractility ; and its retraction on a 
section exemplifies the contractility of or- 
ganization. The internal organs of the 
body have only the three last powers, and 
the white organs (cartilage, tendon, liga- 
ment, &c.) only the two last. While, 
therefore, the two first properties exist 
only in certain parts, tlie latter are found 
in all. Hence tlie brgauie insensible con- 
tractility may be selected as the general 
character of all living parts ; and the con- 
tractility of organization as the common 
attribute of all living or dead parts that are 
organically constructed. 
As for porosity, divisibility, elasticity, 
and the other properties which living bo- 
dies have in common with inanimate mat- 
ter ; they hardly deserve mention here, be- 
cause they are never exerted in their whole 
extent, or in their genuine purity, if we 
may use that phrase. Their results are al- 
ways affected by the influence of the vital 
powers, which constantly modify those ef- 
fects which seem to flow most directly 
from physical, mechanical, or chemic^ 
causes. 
Digestion. Is a function common to all 
animals, by which foreign substances, intro- 
duced into their bodies, and submitted to 
the action of certain organs, change their 
