conclude that plants in a state of nature and growing in exposed
situations, would not make their revolutions during very stormy
weather. A decrease in temperature always caused a considerable
retardation in the rate of revolution; but Dutrochet (tom. xvii. pp.
994, 996) has given such precise observations on this head with
respect to the common pea that I need say nothing more. When twining
plants are placed near a window in a room, the light in some cases
has a remarkable power (as was likewise observed by Dutrochet, p.
998, with the pea) on the revolving movement, but this differs in
degree with different plants; thus Ipomoea jucunda made a complete
circle in 5 hrs. 30 m.; the semicircle from the light taking 4 hrs.
80 m., and that towards the light only 1 hr. Lonicera brachypoda
revolved, in a reversed direction to the Ipomoea, in 8 hrs.; the
semicircle from the light taking 5 hrs. 23 m., and that to the light
only 2 hrs. 37 m. From the rate of revolution in all the plants
observed by me, being nearly the same during the night and the day, I
infer that the action of the light is confined to retarding one
semicircle and accelerating the other, so as not to modify greatly
the rate of the whole revolution. This action of the light is
remarkable, when we reflect how little the leaves are developed on
the young and thin revolving internodes. It is all the more
remarkable, as botanists believe (Mohl, p. 119) that twining plants
are but little sensitive to the action of light.

I will conclude my account of twining plants by giving a few
miscellaneous and curious cases. With most twining plants all the
branches, however many there may be, go on revolving together; but,
according to Mohl (p. 4), only the lateral branches of Tamus
elephantipes twine, and not the main stem. On the other hand, with a
climbing species of Asparagus, the leading shoot alone, and not the