tentacles forming the spokes, and the glands united in a mass over the phosphate representing the axles.  The precision with which each tentacle pointed to the particle was wonderful; so that in some cases I could detect no deviation from perfect accuracy.  Thus, although the short tentacles in the middle of the disc do not bend when their glands are excited in a direct manner, yet if they receive a motor impulse from a point on one side, they direct themselves to the point equally well with the tentacles on the borders of the disc.

In these experiments, some of the short tentacles on the disc, which would have been directed to the centre, had the leaf been immersed in an exciting fluid, were now inflected in an exactly opposite direction, viz. towards the circumference.  These tentacles, therefore, had deviated as much as 180o from the direction which they would have assumed if their own glands had been stimulated, and which may be considered as the normal one.  Between this, the greatest possible and no deviation from the normal direction, every degree could be observed in the tentacles on these several leaves.  Notwithstanding the precision with which the tentacles generally were directed, those near the circumference of one leaf were not accurately directed towards some phosphate of lime at a rather distant point on the opposite side of the disc.  It appeared as if the motor [page 246] impulse in passing transversely across nearly the whole width of the disc had departed somewhat from a true course.  This accords with what we have already seen of the impulse travelling less readily in a transverse than in a longitudinal direction.  In some other cases, the exterior tentacles did not seem capable of such accurate movement as the shorter and more central ones.

Nothing could be more striking than the appearance of the above four leaves, each with their tentacles pointing truly to the two little masses of the phosphate on their discs.  We might imagine that we were looking at a lowly organised animal seizing prey with its arms.  In the case of Drosera the explanation of this accurate power of movement, no doubt, lies in the motor impulse radiating in all directions, and whichever side of a tentacle it first strikes, that side contracts, and the tentacle consequently bends towards the point of excitement.  The pedicels of the tentacles are flattened, or elliptic in section.  Near the bases of the short central tentacles, the flattened or broad face is formed of about five longitudinal rows of cells; in the outer tentacles of the disc it consists of about six or seven rows; and in the extreme marginal tentacles of above a dozen rows.  As the flattened bases are thus formed of only a few rows of cells, the precision of the movements of the tentacles is the more remarkable; for when the motor impulse strikes the base of a tentacle in a very oblique direction relatively to its broad face, scarcely more than one or two cells towards one end can be affected