226 ON VEGETABLE ORGANOGRAPHY AND PHYSIOLOGY. 
autumn. Surely you have forgotten that every animal and vegetable, 
nay, every different part composing these organised bodies, have exist¬ 
ence long before they are visible to the naked eye, or even to the best 
microscopes. You lay great stress on the agency of the 'principle of 
life in vegetables, and speak of it as if it were a thing or member of the 
plant, endowing it with physical power, so that it can “ make annual 
additions to the size of a ligneous plant.” But this, you must be 
aware, is impossible. We know nothing of life but as an effect, or 
motion ; and motion is not a thing which can either add to or abstract 
from the body or frame which it expands and vivifies. Remember, 
amplification is not creation. 
You have, we beg leave to add, puzzled yourself unnecessarily with 
the comparison between the sap of plants and the blood of animals, 
admitting the difficulty of accounting for the change of the former into 
alburnum, on chemical principles, and adding that it is exactly like 
“ the mutation of blood ” into the bones of animals. But here you are 
in the clouds! for who has ever proved that bones are formed of blood, 
or that wood is formed of sap ? Depend upon it, they are both mere 
assumptions: and, because blood and sap are the nourishing fluids of 
both the animal and vegetable systems, the actual formation of the 
solids have been attributed to be only mutations of the fluids, while it 
is well known that both are formed simultaneously. 
You desire to know whether by the analysis of the indusium, we 
have discovered the constituent parts of liber and alburnum? We 
answer that, in the earlier stages of its growth, these parts are too 
minute and colourless to be seen distinctly ; but, towards the end of 
August, they begin to be visible, and shortly afterwards complete. So, 
if in the beginning of this month you had dissected the embryo~fruit in 
a peach-flower, although you might detect the faint form of the stone 
and kernel, it is not likely that you could distinguish the thin film 
which envelopes the latter; but who would, therefore, deny its exist¬ 
ence ? Another question of similar import is added, viz. whether, e: in 
the farinaceous substance of a seed, we have ever detected the ligneous 
consistence of a tree?” It would be very wonderful indeed if we did, 
because, as you must know, the ligneous membranes of the future plant 
do not lie among the farinaceous matter of the cotyledons, but on the 
point of the plumlet and little radicle situated between. Your last 
challenge, about whether we could, by any chemical process, bring a 
dead seed to life again? must go unanswered; for, though we might 
try our hand on a seed or a plant which had been asleep for a hundred 
years, we could not attempt the resuscitation of the dead. 
