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286 THE WILL IN NATURE.
circle round a tree-trunk and to observe whether they all
crept towards the trunk centripetally. On the 6th Nov.
1843, Dutrochet read a treatise on this subject in the
"
"
"
Acad. de Sciences called Sur les Mouvements E-evolutifs
spontanes chez les Vegetaux," which, notwithstanding its
great length, is well worth reading, and is published
among the "Cornptes rendus des Seances de 1*Academic
"
des Sciences for Nov. 1843. The result is, that in pisum
sdtivum (green pea), in bryonia alba (wild bryony) and in
cucumis sativus (cucumber) the stems of those leaves
which bear the tendrils, describe a very slow circular
movement in the air, the time in which they complete an
ellipsis varying from one to three hours according to tem
perature. By this movement they seek at random for
solid bodies round which, when found, they twine their
tendrils ; these then support the plant, it being unable to
stand by itself without help. That is, they
do the same
thing as the eyeless caterpillar, which when seeking a leaf
describes circles in the air with the upper part of its body.
Dutrochet contributes a good deal of information too con-
cerning other movements in plants
in this treatise : for
instance, that stylidium graminifolium in New Holland,
has a column in the middle of its corolla which bears the
anthers and stigma and alternately folds up and unfolds
again. What Treviranus adduces is to the same effect :*
In parnassia palustris and in ruta graveolens, the stamina
incline one after the other, in saxifraga tridactylites in
pairs, towards the stigma, and erect themselves again in.
the same order." Shortly before however, we read in
Treviranus with reference to this : subject
" Of all appa
rently voluntary movements of plants, the direction of
their boughs and of the upper surface of their leaves
towards the light and towards moist heat, and the twining
1
Treviranus,
" Die Erscheinungen und Gesetze des Organischen
"
Lebens (Phenomena and Laws of Organic Life), vol. i. p.
1 73.