The plants which spread very much have the angles of the spaces
which divide their branches more obtuse in proportion as their point
of origin is lower down; that is nearer to the thickest and oldest
portion of the tree. Therefore in the youngest portions of the tree
the angles of ramification are more acute. [Footnote: Compare the
sketches on the lower portion of Pl. XXVII, No. 2.]
404.
The tips of the boughs of plants [and trees], unless they are borne
down by the weight of their fruits, turn towards the sky as much as
possible.
The upper side of their leaves is turned towards the sky that it may
receive the nourishment of the dew which falls at night.
The sun gives spirit and life to plants and the earth nourishes them
with moisture. [9] With regard to this I made the experiment of
leaving only one small root on a gourd and this I kept nourished
with water, and the gourd brought to perfection all the fruits it
could produce, which were about 60 gourds of the long kind, andi set
my mind diligently [to consider] this vitality and perceived that
the dews of night were what supplied it abundantly with moisture
through the insertion of its large leaves and gave nourishment to
the plant and its offspring--or the seeds which its offspring had
to produce--[21].
The rule of the leaves produced on the last shoot of the year will
be that they will grow in a contrary direction on the twin branches;
that is, that the insertion of the leaves turns round each branch in
such a way, as that the sixth leaf above is produced over the sixth
leaf below, and the way they turn is that if one turns towards its
companion to the right, the other turns to the left, the leaf
serving as the nourishing breast for the shoot or fruit which grows
the following year.
[Footnote: A French translation of lines 9-12 was given by M.
RAVAISSON in the _Gazette des Beaux Arts_, Oct. 1877; his paper also
contains some valuable information as to botanical science in the
ancient classical writers and at the time of the Renaissance.]
405.
The lowest branches of those trees which have large leaves and heavy
fruits, such as nut-trees, fig-trees and the like, always droop
towards the ground.
The branches always originate above [in the axis of] the leaves.
406.
The upper shoots of the lateral branches of plants lie closer to the
parent branch than the lower ones.
407.
The lowest branches, after they have formed the angle of their
separation from the parent stem, always bend downwards so as not to
crowd against the other branches which follow them on the same stem
and to be better able to take the air which nourishes them. As is
shown by the angle _b a c_; the branch _a c_ after it has made the
corner of the angle _a c_ bends downwards to _c d_ and the lesser
shoot _c_ dries up, being too thin.
The main branch always goes below, as is shown by the branch _f n
m_, which does not go to _f n o_.
The forms of trees (408--411).
408.
The elm always gives a greater length to the last branches of the
year's growth than to the lower ones; and Nature does this because
the highest branches are those which have to add to the size of the
tree; and those at the bottom must get dry because they grow in the
shade and their growth would be an impediment to the entrance of the
solar rays and the air among the main branches of the tree.
The main branches of the lower part bend down more than those above,
so as to be more oblique than those upper ones, and also because
they are larger and older.
409.
In general almost all the upright portions of trees curve somewhat
turning the convexity towards the South; and their branches are
longer and thicker and more abundant towards the South than towards
the North. And this occurs because the sun draws the sap towards
that surface of the tree which is nearest to it.
And this may be observed if the sun is not screened off by other
plants.
410.
The cherry-tree is of the character of the fir tree as regards its
ramification placed in stages round its main stem; and its branches
spring, 4 or five or 6 [together] opposite each other; and the tips
of the topmost shoots form a pyramid from the middle upwards; and
the walnut and oak form a hemisphere from the middle upwards.
411.
The bough of the walnut which is only hit and beaten when it has
brought to perfection...
[Footnote: The end of the text and the sketch in red chalk belonging
to it, are entirely effaced.]
The insertion of the leaves (412--419).
412.