THE PRINCIPLE OF VITAL AFFINITY. 341 
out being able to remount to the origin of this kind of action in this, as in others 
of the sciences lately called paleetiological. 
4. That the first essential condition necessary for the development of all or- 
ganized life, is that vital affinity by which, under the influence of light, the cells 
of vegetables appropriate and decompose the carbonic acid of the atmosphere, fix 
the carbon, and attach to it the elements of water, so as to form amylaceous 
matter. 
5. That the ulterior changes, effected within organized structures, by which 
oily, albuminous, gelatinous, and perhaps extractive compounds, are formed and 
assimilated to the living textures, appear to belong to certain definite vital affini- 
ties of the carbon, originally fixed from the air, and which is the basis of all or- 
ganized substances, not only for the elements of water, but for hydrogen, for azote, 
for sulphur, phosphorus, and various salts; that most or all these ulterior 
changes are effected both in vegetables and animals; and that the oxygen taken 
in by the organs of respiration, although it may be necessary to the play of all 
the different affinities in living bodies, appears hardly to enter, if it enter at all, 
into the constitution of any of the compounds thus formed and applied to the 
nourishment of the textures. 
6. That these compounds, in order that they may be applied to this purpose, 
must be moved within living bodies, and applied, in the fluid form, to the textures 
which they are to nourish, although in various instances, both in vegetable and ani- 
mal life, they have themselves the solid form; and that the requisite fluidity is 
given by various contrivances, chiefly seen in the prome vie of animals,—by me- 
chanical attrition, by incipient decomposition of the materials employed, but espe- 
cially by a simply chemical solution of these,—for which purpose certain parts of 
living structures are endowed with a vital power of separating acids, and others of 
separating alkalies out of the compound fluids pervading them, and thus prepar- 
ing solvents for those solids. 
7. That the vital affinities do not, strictly speaking, supersede ordinary che- 
mical affinities in the living animal body, but are superadded to them, so that 
the ingesta, as they come under their influence, are divided between the combi- 
nations to which those different kinds of affinity dispose them, and _parti- 
cularly are partly under the influence of the substances exerting vital affinities, 
and partly of the oxygen of the air, brought to them by the arterial blood ; and that 
as these ingesta often contain large quantities of matter, especially of non- 
azotised matter, either inapplicable to the formation of the animal compounds, 
or redundant, these portions, fall immediately under the influence of the oxygen, 
and form one source of the excretions from the animal body. 
8. That the vital affinities, like all living properties, are liable to an influ- 
ence of place and of time, which is not seen in the inorganic world, but is an es- 
sential attribute of the organized Creation, which has been superadded, in later 
times, to the original arrangements of the universe. They are acquired by por- 
VOL. XVI. PART III. 4k 
