and at the same time the mark beneath, it was necessary to cut off three leaves on one side.  We do not know whether it was owing to this cause, or to the plant having previously become bent to one side through heliotropism, but from the morning of the 7th of March to 10.30 P.M. on the 8th, the stem moved a considerable distance in a zigzag line in the same general direction.  During the night of the 8th it moved to some distance at right angles to its former course, and next morning (9th) stood for a time almost still.  At noon on the 9th a new tracing was begun (see Fig. 71), which was continued till 8 A.M. on the 11th.  Between noon on the 9th and 5 P.M. on the 10th (i.e. in the course of 29 h.), the stem described a circle.  This plant therefore circumnutates, but at a very slow rate, and to a small extent.

(5.) Tropaeolum majus (?) (dwarfed var. called Tom Thumb); (Geraniaceae, Fam. 47).—­The species of this genus climb by the [page 204] aid of their sensitive petioles, but some of them also twine round supports; but even these latter species do not begin to circumnutate in a conspicuous manner whilst young.  The

Fig. 72.  Tropaeolum majus (?):  circumnutation of stem of young plant, traced on a horizontal glass from 9 A.M.  Dec. 26th to 10 A.M. on 27th.  Movement of bead magnified about 5 times, and here reduced to half of original scale.

variety here treated of has a rather thick stem, and is so dwarf that apparently it does not climb in any manner.  We therefore wished to ascertain whether the stem of a young plant, consisting of two internodes, together 3.2 inches in height, circumnutated.  It was observed during 25 h., and we see in Fig. 72 that the stem moved in a zigzag course, indicating circumnutation.

Fig. 73.  Trifolium resupinatum:  circumnutation of stem, traced on vertical glass from 9.30 A.M. to 4.30 P.M.  Nov. 3rd.  Tracing not greatly magnified, reduced to half of original size.  Plant feebly illuminated from above.

(6.) Trifolium resupinatum (Leguminosae, Fam. 75).—­When we treat of the sleep of plants, we shall see that the stems in several Leguminous genera, for instance, those of Hedysarum, Mimosa, Melilotus, etc., which are not climbers, circumnutate in a conspicuous manner.  We will here give only a single instance (Fig. 73), showing the circumnutation of the stem of a large plant of a clover, Trifolium resupinatum.  In the course of 7 h. the stem changed [page 205] its course greatly eight times and completed three irregular circles or ellipses.  It therefore circumnutated rapidly.  Some of the lines run at right angles to one another.

Fig. 74.  Rubus (hybrid):  circumnutation of stem, traced on horizontal glass, from 4 P.M.  March 14th to 8.30 A.M. 16th.  Tracing much magnified, reduced to half of original size.  Plant illuminated feebly from above.