In Monocotyledons a similar advance from hypogyny to epigyny is observed, and from the dorsiventral to the radial type of flower.
They act on organs which exhibit all degrees of physiological differentiation, from the radial to the dorsiventral.
A dorsiventral organ, moreover, exhibits a torsional movement under lateral stimulus of gravity.
Thick lines represent the more excitable side of an anisotropic or dorsiventral organ.
In a dorsiventral organ the geotropic excitabilities of the upper and lower sides are different.
A stimulus will be called lateral when it acts on either the right or left flank of a dorsiventral organ.
The differential excitabilities of a dorsiventral organ modifies its position of geotropic equilibrium.
We shall presently find that a dorsiventral organ responds to lateral stimulus by torsion.
The internal structure of bilateral or dorsiventral organs is largely determined by the direction of the rays.
Lateral stimulus induces a torsional response in a dorsiventral organ.