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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 law of proportion in the growth of the branches (396--402).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.
206:201 : The sketches illustrating this are on the right hand side of Pl. XXVII, No. I, and the text is also given there in facsimile.