The leaves, whilst very young, on the leading shoots of the Carnation (Dianthus caryophyllus) are highly inclined or vertical; and if the plant is growing vigorously they diverge so quickly that they become almost horizontal in a day.  But they move downwards in a rather oblique line and continue for some time afterwards to move in the same direction, in connection, we presume, with their spiral arrangement on the stem.  The course pursued by a young leaf whilst thus obliquely descending was traced, and the line was distinctly yet not strongly zigzag; the larger angles formed by the successive lines amounting only to 135o, 154o, and 163o.  The subsequent lateral movement (shown in Fig. 96, p. 231) was strongly zigzag with occasional circumnutations.  The divergence and sinking of the young leaves of this plant seem to be very little affected by geotropism or heliotropism; for a plant, the leaves of which were growing rather slowly (as ascertained by measurement) was laid horizontally, and the opposite young leaves diverged from one another symmetrically in the usual manner, without any upturning in the direction of gravitation or towards the light.

The needle-like leaves of Pinus pinaster form a bundle whilst young; afterwards they slowly diverge, so that those on the upright shoots become horizontal.  The movements of one such [page 270] young leaf was traced during 4 ½ days, and the tracing here given (Fig. 121) shows that it descended at first in a nearly straight line, but afterwards zigzagged, making one or two little loops.  The diverging and descending movements of a rather older leaf were also traced (see former Fig. 113, p. 251):  it descended during the first day and night in a somewhat zigzag line; it then circumnutated round a small space and again descended.  By this time the leaf had nearly assumed its final position, and now plainly circumnutated.  As in the case of the Carnation, the leaves, whilst very young, do not seem to be much affected by geotropism or heliotropism, for those on a young plant laid horizontally, and those on another plant left upright, both kept in the dark, continued to diverge in the usual manner without bending to either side.

Fig. 121.  Pinus pinaster:  epinastic downward movement of a young leaf, produced by a young plant in a pot, traced on a vertical glass under a skylight, from 6.45 A.M.  June 2nd to 10.40 P.M. 6th.

With Coboea scandens, the young leaves, as they successively diverge from the leading shoot which is bent to one side, rise up so as to project vertically, and they retain this position for some time whilst the tendril is revolving.  The diverging and ascending movements of the petiole of one such a leaf, were traced on a vertical glass under a skylight; and the course pursued was in most parts nearly straight, but there were two [page 271] well-marked zigzags (one of them forming an angle of 112o), and this indicates circumnutation.