235 
BOOK 11. 
PHYSIOLOGY ; OR, PLANTS CONSIDERED IN A STATE 
OF ACTION. 
GENERAL CONSIDERATIONS. 
W^E have thus far considered plants as inert bodies, having 
certain modifications of structure, and formed upon a plan, 
the simplicity and uniformity of which is among the most 
beautiful proofs of the boundless power and skill of the Deity. 
Our next business is to enquire into the nature of their 
vital actions, and to consider those phenomena in which the 
analogy that undoubtedly exists between plants and animals 
is most striking ; in a word, to make ourselves acquainted 
with the exact nature of the laws of vegetable life. 
In explaining these things, it is not my purpose to notice all 
the different speculations that ingenious men have from time 
to time brought forward : for this would be incompatible with 
the plan of my work, and would be far more curious than 
useful. On the contrary, I propose, in the first place, to give 
a summary exposition of the principal phenomena of vegeta- 
tion, and then to support the statement by a detailed account 
of the more important proofs of all doubtful points. 
In this I have been most materially assisted by the Physio- 
logie Vegetale of De Candolle, a work of which it is difficult to 
speak in terms of sufficient eulogy, but which I feel quite 
justified in describing as the most important production on 
the subject of Vegetable Physiology, since the appearance of 
the Physique des Arhres of Duhamel. 
If we place a seed — that of an apple for instance — in 
earth at the temperature of 32® Fahr., it will remain inactive 
till it finally decays. But if it is placed in moist earth above 
