195 
Book IV. 
How they 
are produ 
ced. 
VEGETATION. 
important parts of the plant. Accordingly we find, 
that whenever we strip a plant of its leaves, we strip it 
entirely of its vegetating powers till new leaves are 
formed. It is well known, that when the leaves of 
plants are destroyed by insects, they vegetate no longer, 
and that their fruit never makes any farther progress in 
ripening, but decays and dries up. Even in germina 
tion no progress is made in the growth of the stem till 
the seed leaves appear. As much food indeed is laid up 
in the cotyledons as advances the plant to a certain 
state ; the root is prepared, and made ready to perform 
its functions ; but the sap which it imbibes must be 
first carried to the seed leaves, and digested there, be 
fore it be proper for forming the plumula into a stem. 
Accordingly if the seed leaves are cut off, the plant re 
fuses to vegetate. 
It will be very natural to ask, If this be true, how 
come the leaves themselves to be produced ? Even if no 
answer could be given to this question, it could not over 
turn a single fact which has been mentioned, nor affect 
a single conclusion as far as it has been fairly deduced 
from these facts. We know that the leaves exist long 
before they appear; they have been traced even five 
years back. They are completely formed in the bud, 
and fairly rolled up for evolution, many months before 
that spring in which they expand. We know, too, that 
if we take a bud, and plant it properly, it vegetates, 
forms to itself a root, and becomes a complete plant. 
It will not be said, surely, that in this case the bud im 
bibes nourishment from the earth ; for it has to form a 
root before it can obtain nourishment in that manner ; 
and this root cannot be formed without nourishment. 
Is not this a demonstration that the bud contains, al¬