343 
PHYSIOLOGY. 
the fkin of one part by that of the neighbouring organs; 
the alveoli of the jaws by the teeth. See. Mow, if any of 
thefe caufes ceafe to aft, contraction immediately takes 
place ; divide a mufcle, and its antagonift will be fhortened; 
empty a hollow mufcular organ, and it will contract; pre¬ 
vent an artery from receiving blood, and it will be con¬ 
verted into a ligament; cut the fkin, and the edges of 
the incifion will be drawn afunder; remove a tooth, and 
the focket will be obliterated. 
In all thefe cafes contraction follows the ceflation of a 
natural extenfion; in other inftances it is the confequence 
of the ceflation of an unnatural extenfion. Thus the ab¬ 
domen is reduced after parturition, or paracentefis ; the 
cellular tifl'ue, after the opening of an abfeefs; the tu¬ 
nica vaginalis after the operation for hydrocele ; the fkin 
of the ferotum after the removal of a large difeafed tefti- 
cle ; and aneuriftnal facs after the evacuation of the con¬ 
tained fluid. 
This kind of contraftility is perfectly independent of 
life; like the extenfibility, it is connected only to the tif- 
fue or organic arrangement of parts : but the vital powers 
beftow on itincreafed energy ; thus a divided mufcle re- 
traCts much lefs in the dead than in the living ftate. It 
terminates only by the diforganization of the parts from 
decompolition, &c. and not by the annihilation of their 
vital properties. 
Moll authors, as Haller, Blumenbacb, Barthez, &c. 
have confounded the phenomena of this contractility with 
thofe of the organic infenfible kind, or tonicity; they refer 
the reduction of the abdomen after its diftenrion, the re- 
traCtion of the divided fkin, and the corrugation of the 
ferotum by cold, and the crifpation of parts by certain 
poifons, ftyptics, &c. to the fame principle. The two 
former phenomena belong to the contractility of tiffue, 
which never fuppofes the application of irritants; the 
latter to tonicity, which is never exerted without their 
influence. 
The general refult of the preceding remarks on the vi¬ 
tal properties, is exhibited in the following Table, which 
prefents all thefe properties in one point of view. 
ClaJJes. 
I. Vital 
Genera. 
i. Senfibility 
Species. Varieties. 
5 i. Animal. 
{ z. Organic. 
- S 1 - Animal { i. Senfible. 
z. Contraftility j a> 0rganic * 2 . i n f enflble . 
( i. Extenfibility. 
II. Of tifl'ue/ 
i 2. Contractility. 
We are prevented from contrafting with this arrange¬ 
ment the more beautiful as well as more generally appli¬ 
cable one of John Hunter, becaufe we have already intro¬ 
duced that under the article Pathology; (fee vol. xix. 
p. 35.) It remains only to obferve that the arrangement 
of Cuvier is entirely founded on that of Hunter, as may 
be feen by comparing the page juft referred to, with the 
following analyfis of Cuvier’s fyftem. The whole work 
is divided into Thirty LeCtnres. The firft is occupied 
with preliminary obfervations on the animal economy, 
comprehending a general view of the functions of animal 
bodies; a general idea of the organs of which the animal 
body .is compofed ; a view of the principal differences 
exhibited by thefe organs, and of the relations which exift 
among thofe variations, together with a divifion of ani¬ 
mals founded on their organization. The fecond leCture 
treats of the organs of motion in general ; the third, 
fourth, fifth, and fixth, leCtures, are merely anatomical, 
exhibiting a comparative view of thefe organs in the 
feveral clafies of animals. The feventh leCture is ftriCily 
phyfiological, and treats of the organs of motion confi- 
dered in the feveral aCtions of Handing, walking, feizing, 
and climbing, leaping, fwimming, and flying. 
The eighth, ninth, tenth, eleventh, twelfth, thirteenth, 
fourteenth, and fifteenth, leCtures, are occupied in confi- 
deringthe anatomy and phyfiologyof the function of fen- 
fation. Of thefe, part of the ninth treats of the nervous 
fyftem in general, and of its aCtion; part of the twelfth 
gives the phyfiology of vifion ; part of the thirteenth, that 
of hearing; part of the fourteenth, that of touch; and 
part of the fifteenth, that of fmell and tafte. 
The fixteenth, feventeenth, eighteenth, nineteenth, 
twentieth, and twenty-firft, leCtures, treat of the organs 
and phenomena of digeftion, maltication, infalivation. 
and deglutition. The twenty-fecond leCture treats of 
what have been called the afliftant chylopoietic vifeera ; 
namely, the liver, the pancreas, the fpleen, and their 
offices. The twenty-fourth treats of the organs and 
phenomena of circulation in general; the twenty-fixth 
of thofe of refpiration in general; the twenty-eighth of 
the organs of voice. The twenty-ninth treats of the 
organs and phenomena of generation ; and the thirtieth, 
of thofe of excretion, comprehending a general view 
both of fecretion and excretion. 
This hiftorical Iketch will probably appear unfatisfac- 
tory and incomplete; but it mult be recollected that, in 
the large article juft referred to, we have detailed the 
difeoveries of all practical faCts, and that the prefent view 
is merely confined to certain fpeculative opinions or 
methods of arrangement. 
It would be an interefting difeuffion, were we to enter 
into a comparifon of the preceding fyltems and arrange¬ 
ments; and, by pointing out in what particulars each 
author is deficient, lay the foundation of fome better 
method. Our limits not admitting this, it fuffices to fay, 
that thofe arrangements founded on a claffification of func¬ 
tions feem to us inferior to fuel) as are formed on a view 
of the different JlruElures of animals; and that, accor¬ 
dingly, the latter fpecies of arrangement will be adopted 
by us. The author of this article makes no apology for 
the introduction of the following method, fince the ac¬ 
knowledged failure of other phyfiological arrangements 
warrants any attempt at improvement. 
I. Of the Elementary Structures of the Human Body. 
Many attempts have been made unfuccefsfully to dif- 
cover the elements of the animal economy. The chemift, 
on the one hand, and the microfcopical obferver on the 
other, have each in their turn amuled themfelves with 
reveries on this important fubjeCt. But the chemift: 
forgets that, in the delicate matter of which we now dif- 
courfe, changes are induced by his procefles which effec¬ 
tually elude his refearches ; that, at the time the body 
lofes its aCtion, it lofes alfo fomething either of its ftruc- 
ture or of the addenda of ftruCture of which his fcience 
can take no account. The microfcope has difplayed 
much information to our view ; but, as far as regards the 
difeovery of elementary or ultimate parts, the contradic¬ 
tions of all the different parties who have attempted its 
ufe l’ufficiently manifeft its infufficiency. 
From both the laboratory and the microfcope, however, 
much knowledge of elementary parts is to be gained. 
The great error that has happened to their employers has 
been, that they have not precifely underftood what they 
were looking for. They do not feem to have confidered 
that, as the body is ultimately refolvable into the com¬ 
mon elements of matter by chemical procefles, fo there 
is an intermediate ftate of combination in which alone it 
is fitted for the purpofes of aCtion. It feeros to us, that 
this intermediate ftate is to be learnt chiefly from obfer- 
ving the afls of the animal, and that we fhould define an 
elementary ftruCture to be fuch as performs a Ample aCt 
or motion. This view of the fubjeCt accords alfo with 
the aCtual appearances which difl'eCtion furnifhes ; re¬ 
ceives fome confirmation from chemiftry, as well as from 
microfcopical obfervations; and agrees with the pheno¬ 
mena of the formation of the feetus. At the fame time 
it mult be confefled that in the detail this divifion does 
not feem very accurate; for conjectures perpetually 
occur as to the ulterior caufes of motion, which , is true, 
would 
