1864.] Carrenrer on Correlation of Physical and Vital Forces. 259 
ON THE APPLICATION OF THE PRINCIPLE OF “CON- 
SERVATION OF FORCE” TO PHYSIOLOGY. 
Parr II. (conclusion): The Relations of Light and Heat to the Vital 
Forces of Animals. 
By Wit11am B. Carrenter, M.D., F.R.S., F.LS., F.G.S. 
Tose of our readers who accompanied us through the first part of our 
inquiry are aware that it was our object to show, that as Force is 
never lost in the Inorganic World, so Force is never created in the 
Organic ; but that those various operations of Vegetable life which are 
sometimes vaguely attributed to the agency of an occult “ Vital Prin- 
ciple,” and are referred by more exact thinkers to certain Vital Forces 
inherent in the organism of the Plant, are really sustained by Solar 
Light and Heat. These, we have argued, supply to each germ the 
whole power by which it builds itself up, at the expense of the materials 
it draws from the Inorganic Universe, into the complete organism ; 
while the mode in which that power is exerted (generally as Vital 
Force, specially as the determining cause of the form peculiar to each 
type) depends upon the ‘germinal capacity’ or directive agency in- 
herent in each particular germ. The first stage in this constructive 
operation consists in the production of certain Organic Compounds of 
a purely Chemical nature—such as gum, starch, sugar, chlorophyll, oil, 
and albumen—at the expense of the oxygen, hydrogen, carbon, and 
nitrogen, derived from the Water, Carbonic Acid, and Ammonia of the 
atmosphere; whilst the second consists in the further elevation of a 
portion of these organic compounds to the rank of Organized Tissue pos- 
sessing attributes distinctively Vital. Of the whole amount of Organic 
Compounds generated by the Plant, it is but a comparatively small 
part (a) that undergoes this progressive metamorphosis into living 
tissue. Another small proportion (b) undergoes a retrograde meta- 
morphosis, by which the original binary components are reproduced; and 
in this descent of Organic Compounds to the lower plane, the power 
consumed in their elevation is given forth in the form of Heat and 
Organizing Force (as is specially seen in Germination), which help to 
raise the portion a to a higher level. But by far the larger part (c) of 
the Organic Compounds generated by Plants remains stored up in their 
fabric, without undergoing any further elevation; and it is at the 
expense of these, rather than of the actual tissues of Plants, that the 
life of Animals is sustained. 
When, instead of yielding up any portion of its substance for the 
sustenance of Animals, the entire Vegetable organism undergoes retro- 
grade metamorphosis, it not only gives back to the Inorganic World 
the binary compounds from which it derived its own constituents, but 
in the descent of the several components of its fabric to that simple con- 
dition—whether by ordinary combustion (as in the burning of Coal) or 
by slow decay—it gives out the equivalents of the Light and Heat by 
which they were elevated in the first instance. 
In applying these views to the interpretation of the phenomena of 
