PHYSIOLOGY. 
furnished to it by the skin and alimentary 
canal, by a particular set of vessels, called 
lymphatics ; in the same vray it receives 
also the particles detached from various 
organs, in order to be sent out of the body 
by the different secretions. 
The air entering the lungs seems to pro- 
duce a sort of combustion in the venous 
blood, which is necessary for the support of 
life in all organized bodies. Vegetables, 
and such animals as have no circulation, re- 
spire (for that is the name given to this ac- 
tion of the atmosphere on the nutritive 
fluid) by their whole surface, or by means 
of particular vessels which convey air into 
the interior of the body. Those only, which 
enjoy “ true circulation, breathe by means 
Of a particular organ; because, in them, 
the blood constantly flowing to and from a 
common source, its vessels have been so 
arranged, that it is not distributed to the 
other parts of the body until after passing 
through the lungs ; a circumstance which 
could not take place where the nutritive 
fluid is distributed uniformly through the 
body without being contained in vessels. 
Thus respiration is a function of a third or- 
der, depending entirely oji circulation, and 
arising as a remote consequence from the 
faculties which characterise animals. 
Generation is the only process in animals, 
the mode of which does not depend on 
tlieir peculiar faculties, at least as far as the 
fecundation of the germs is concerned. 
Their power of moving and approaching to 
each other, of desiring and feeling, has al- 
lowed them to receive all the enjoyments 
of love, while the spermatic fluid is convey- 
ed uncovered immediately upon the germs ; 
in vegetables, on the contrary, which have 
no power of propelling this fluid, it is in- 
closed in small capsules capable of being 
transported by the wind, and forming what 
is called the dust of the stamina. Thus, 
while tire organs of the other functions are 
more complicated in animals, on account 
of their peculiar functions, generation is ex- 
ercised in them, for the very same reason, 
in a more simple way than in vegetables. 
Such are the principal functirms that 
compose the animal economy ; they have 
usually been arranged in three orders. 
Some of them constitute animals what they 
are, render them proper to till the space 
which nature has marked out for them in 
the general arrangement of the universe, 
and would be sufficient for their existence, 
if that were momentary. These are the fa- 
culties of sensation and motion ; of which 
the former determines them in the choice 
of such actions as they are capable of, and 
the latter enables them to execute these ac- 
tions. Each animal may then be consider- 
ed as a partial machine, co-ordinate to all 
the other machines, which, by their .assem- 
blage, from this world ; the organs of mo- 
tion are the wheels and levers : in a word, 
all the passive parts ; but the active prin- 
ciple, the spring which sets all in motion, 
resides only in the sensitive faculty, with- 
out which the animal would be lost in a 
constant sleep, and be really reduced to a 
merely vegetative life. These two fuuctions, 
then, form the first order, or the animal 
functions. 
But the animal machine, in addition to 
the powers which those of human construc- 
tion possess, is endowed with a principle of 
preservation and repair, consisting in the 
assemblage of functions which contribute 
to nutrition, viz. digestion, absorption, cir- 
culation, respiration, and secretion ; these 
form the second order, or the vital func- 
tions. Lastly, as the duration of each ani- 
mal is limited according to its species, the 
generative form a third order of functions, 
by means of which the individuals that pe- 
rish are replaced, and the existence of the 
species preserved. 
This threefold division of the objects of 
physiology is open to many objections, 
which we have not room to consider in this 
place ; and we tlierefore add another more 
complete and natural classification, which 
will be sufficiently explained in the sub- 
joined tabular view.- 
YOL. V. 
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