LIVING BODIES SUBJECT TO CONTINUAL CHANGES. 
13 
mentation. It is true, that J. B. Fray ^ as- 
serts, he has seen infusoria animalculae deve- 
loped in pure water. Gruithuisen ■[■ says, 
also, that he saw generated, in an infusion of 
granite, of chalk, and of marble, a gelatinous 
membrane, in which, after some time, move- 
ments were manifested, and ended Ijy the 
formation of infusoria, of monanes, and glo- 
bular animaculge. But it is very probable 
that the bodies subjected to experiment, 
or the water employed in the infusion, already 
contained organic matter, though in a very 
small quantity, for other naturalists have not 
oKserved the formation of living bodies in in- 
fusions of purely inorganic ones. 
XV. In all inorganic bodies, particularly 
crystals, as soon as their materials are brought 
together and combined by the laws of affinity, 
the chemical composition remains quiet an t 
it is by this very fact that they subsist. It is 
not so with living bodies, the composition of 
which is continually undergoing changes. So 
long as these bodies act after their manner, that 
is, so long as they live, they are receiving within 
them new substances, which’ they assimilate 
and introduce into their composition,from which 
they expel others. It is by the actions of 
assimilation of food, of respiration, of nutri- 
tion, and excretion, that the materials of liv- 
ing bodies are incessantly changing. The 
comrosition of these bodies, therefore, is 
never in a state of quietude. Their tenden- 
cy to assimilate to themselves new sub- 
stances, cease only with the extinction of the 
manifestations of activity, which we call life. 
But at the same time their existence is stayed, 
they are destroyed, and lose their form as 
well as composition. There is then this es- 
sential difference between inorganic and 
living bodies, that the duration of the former 
depends on the repose in which their com- 
position remains, whilst the existence and 
preservation of the latter are conditional 
on a continual change of composition. The 
cause of this difference is found in the pecu- 
liar circumstances, belonging to living bodies, 
which induce new affinities, and which can 
only be maintained in action thereby, whe te- 
as, when bodies not endued with life are once 
formed, no further change takes place in the 
relations of affinity which themselves pro- 
duce. 
XVI. Although during their existence, liv- 
ing bodies are subjected to continual changes, 
rapid or slow, and introduce within themselves 
materials obtained from the atmosphere, from 
matter and from aliments of various kinds, 
and also free themselves of certain substances, (*) 
(*) Essai sur rOrigine des Substances Org-a- 
nisees et Inorg-anisees. Berlin, 1807. — Essai sur 
rOrig’ine des Corps Org-anisees et su < uelques 
Phenomenesde Physiologie Animale et Vegetale 
Paris, 1817. 
(•1) Ueberdie Chemischen und dynainischen. 
Momente bei der Bildung’ der Infnsorien mij 
einer Kutik der Versuche Fray’s : in Gehlen’s 
Journal der Physik, vol. viii. p. 150. 
(t) Nevertheless, when living’ bodies are ex- 
posed to a very high or a very low temperature 
if they be placed in contact with certain kinds 
of gas, or if concentrated mineral acids or caus- 
tic alkalis be made to act on them, they may 
even then be destroyed by these different 
agents. 
nevertheless they preserve, during 'a certain 
lapse of time, the form and composition which 
is peculiar to them. They have thus the 
faculty whilst incessantly changing their com- 
position, of retaining their qualities, and even 
of resisting to a certain extent, chemical influ- 
ences from without, (t) All inorganic bodies, 
on the contrary, being only the simple product 
of affinities, the property of substances which 
constitute them, are deprived of the power of 
re-acting on the external impressions which 
produce changes in them, and are delivered 
up to the play of chemical affinities. For 
instance, when a crystal has been placed in 
contact with an acid which has an affinity 
for its base, the latter combines with the 
acid, in such a manner that the form and com- 
position of the crystal are changed and de- 
stroyed. 
We can attribute this property which or- 
ganic bodies possess of resisting, to a certain 
extent, the purely chemical actions of exter- 
nal things, to no other than peculiar powers 
which sway the affinities. This results from 
the consideration, that so soon as their vital 
powers are extinguished, exterior influences 
guided by the laws of chemical affinities, pro- 
duce likewise in them, changes tending to the 
destruction of the form and composition pe- 
culiar to them. After the death of an or- 
ganized body chemical affinities enter into 
|)lay, so that its form and composition, which, 
during an age or more, had frequently braved 
the destructive action of external things, are 
done away within a short space of time. 
XVII. The chemical operations of pu-. 
trefaction and fermentation, which are esta» 
blished after the extinction of the spe- 
cial powers, whose action counterbalances, 
during the life of organized bodies, that by 
which the chemical affinities of external things 
tend to destroy them, and which change at 
once their composition and their form, are 
phenomena of a particular nature, that are not 
observed in the decomposition of inorganic 
bodies. They are organi co-chemical pro- 
cesses. The decomposition which takes 
place after death has, in ordinary cases, its 
limits, and the organized ma'erials do not 
altogether enter, but only in part into the inor- 
ganic kingdom, since they are neither com- 
pletely reduced to their elements, nor con- 
verted into binary combinations. 
XVIII. The organic combinations or mat- 
ters, albumen, starch, gluten, gum, animal 
mucus, fibrin, gelatin, &c. as well as the ani- 
mal and vegetable tissues into which they 
enter, possess the peculiarity, when placed 
in favourable external circumstances, exposed 
to a certain degree of heat, of light, and hu- 
midity and in contact with the asmosphere, of 
passing to new simple organic forms, as soon 
as they have been detached from the organic 
combination of any being. This is what hap- 
pens in fermentation and putrefaction, where 
the resolution of organic combinations gives 
rise, according to the composition of the latter, 
and external influences sometimes to infusoria, 
sometimes to the green matter of Priestley or 
to mouldiness. This property which organic 
matters enjoy, of taking a new form under 
