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.]