The Notebooks - The Original Classic Edition. Leonardo Da

395.

       Every year when the boughs of a plant [or tree] have made an end of maturing their growth, they will have made, when put together,

       a thickness equal to that of the main stem; and at every stage of its ramification you will find the thickness of the said main stem; as:

       i k, g h, e f, c d, a b, will always be equal to each other; unless the tree is pollard--if so the rule does not hold good.

       All the branches have a direction which tends to the centre of the tree m.

       [Footnote: The two sketches of leafless trees one above another on the left hand side of Pl. XXVII, No. 1, belong to this passage.]

       396.

       If the plant n grows to the thickness shown at m, its branches will correspond [in thickness] to the junction a b in consequence of

       the growth inside as well as outside.

       The branches of trees or plants have a twist wherever a minor branch is given off; and this giving off the branch forms a fork; this said fork occurs between two angles of which the largest will be that which is on the side of the larger branch, and in proportion, unless accident has spoilt it.

       [Footnote: The sketches illustrating this are on the right hand side of PI. XXVII, No. I, and the text is also given there in facsimile.]

       397.

       There is no boss on branches which has not been produced by some branch which has failed.

       The lower shoots on the branches of trees grow more than the upper ones and this occurs only because the sap that nourishes them, being heavy, tends downwards more than upwards; and again, because those [branches] which grow downwards turn away from the shade which exists towards the centre of the plant. The older the branches are, the greater is the difference between their upper and their lower shoots and in those dating from the same year or epoch.

       [Footnote: The sketch accompanying this in the MS. is so effaced that an exact reproduction was impossible.]

       398.

       OF THE SCARS ON TREES.

       The scars on trees grow to a greater thickness than is required by the sap of the limb which nourishes them.

       399.

       The plant which gives out the smallest ramifications will preserve the straightest line in the course of its growth.

       [Footnote: This passage is illustrated by two partly effaced sketches. One of these closely resembles the lower one given under No.

       408, the other also represents short closely set boughs on an upright trunk.]

       400.

       OF THE RAMIFICATION.

       The beginning of the ramification [the shoot] always has the central line [axis] of its thickness directed to the central line [axis] of

       the plant itself.

       401.

       In starting from the main stem the branches always form a base with a prominence as is shown at a b c d.

       402.

       88

       WHY, VERY FREQUENTLY, TIMBER HAS VEINS THAT ARE NOT STRAIGHT.

       When the branches which grow the second year above the branch of the preceding year, are not of equal thickness above the ante-cedent branches, but are on one side, then the vigour of the lower branch is diverted to nourish the one above it, although it may be somewhat on one side.

       But if the ramifications are equal in their growth, the veins of the main stem will be straight [parallel] and equidistant at every degree

       of the height of the plant.

       Wherefore, O Painter! you, who do not know these laws! in order to escape the blame of those who understand them, it will be well that you should represent every thing from nature, and not despise such study as those do who work [only] for money.

       The direction of growth (403-407).

       403.

       OF THE RAMIFICATIONS OF PLANTS.

       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