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Show 372 PINGUICULA VULGARIS. CHAP. XVI. After 4 hrs. 20 m. there was decided incurvation, which increased a little during the afternoon, but was in the same state on the following morning. Near the apex both margins were inwardly curved. I have never seen a case of the apex itself beinO' in the least curved towards the base of the loaf. After 48 h~s. (always reckoning from the time when the flies were placed on the leaf) the margin had everywhere begun to unfold. Experiment 4.-A large fragment of a fly was placed on a leaf, in a medial line, a little beneath the apex. Both lateral margins were perceptibly incurved in 3 hrs., and after 4 hrs. 20m. to such a degree that the fragment was clasped by both margins. <~ After 24 hrs. the two infolded edges near the apex (for the lower part of t.he leaf was not at all affected) were measured and found to be ·11 of an inch (2·794 mm.) apart. The fly was no-\v removed and a stream of water poured over the leaf so as to ' . wash the surface ; and after 24 hrs. the margn1s were ·25 of an inch (6·349 mm.) apart, so that they were largely unfolded. After an additional 24 hrs. they were completely unfolded. Another fly was now put on the same spot to see whether this loaf, on which the first fly had been left 24 hrs., would move again ; after 10 hrs. there was a trace of incurvation, but this did not increase during the next 24 hrs. A bit of meat was also placed on the margin of a leaf, which four days previously had become strongly incurved over a fragment of a fly and had afterwards re-expanded; but the meat did not cause even a trace of jncurvation. On the contrary, the margin became somewhat rcflexed, as if injured, and so remained for the three following days, as long as it was observed. Hxperiment 5.-A large fragment of a fly was placed halfway between the apex and base of a leaf and halfway between the midrib and one margin. A short space of this margin, opposite the fly, showed a trace of incurvation after 3 hrs., and thjs became strongly pronounced in 7 hrs. After 24 hrs. the infolded edge was only ·16 of an inch (4·064 mm.) from the midrib. The margin now began to unfo1d, though the fly was left on the leaf; so that by the next morning (i.e. 48 hrs. from the time when tbe fly was first put on) the infolded edge had almost completely recovered its original position, being now ·3 of an inch (7·62 rom.), instead of ·16 of an inch, from the midrib. A trace of fl exure was, however, still visible. Experiment 6.-A young and concave leaf waR selected with its margins slightly and naturally incurved. Two rather large, oblong, rectangular pieces of roast meat were placed with tbeir ends touching the infolded edge, and ·4G of an inch (11·68 mm.) CHAP. XVI. MOVEMENTS OF THE LEA YES. 373 apart from o;ne another. After 24 hrs. the margin was greatly and equally nwurved (see fig. 16) throughout this space and for a length of ·1~ or ·13 of an inch (3·048 or 3·302 mm.) above ancl below each btt; so that the margin had been o.ffected over a gre~ter length between the two bits, owing to their conjoint actwn, than beyond th~m. The bits of moat were too large to be clasped by the margm, but they were tilted up, one of them Ro as to stand almost vertically. After 48 hrs. the margin was almost unfolded, and the bits had sunk down. \Vhen again examined after two days, the margin was quite unfolded, with the exception of the naturally inflected edge; and one of the bits of meat, the end of which had at first touched the edge, was now ·067 of an inch (1·69 mm.) distant from it; so that this bit had been pushed thus far across the blade of the leaf. Experiment 7.-A bit of meat was placed close to the iucurved edge of a rather young leaf, and after it had re-expanded, the bit was left lying ·11 of an inch (2·794 mm.) from the edge. The distance from the edge FIG 16. to the midrib of the fully expanded leaf (Pinguicula v ulga1·is.) was ·35 of an inch (8·89 mm.); so that the Outline of leaf, with bit had been pushed inwards and across r~~~t margin inflec~ect ] th . d f 't · d' a»amst two square bits near y one- II' o 1 s semi- 1ameter. of meat. Experiment 8.-Cubes of sponge, soaked in a strong infusion of raw meat, were placed in close contact with the incurved edges of two leaves,-an older and younger one. The distance from the edges to the midribs was carefully miasured. After 1 hr. 17m. there appeared to be a trace of incurvation. After 2 hrs. 17 m. both leaves were plainly inflected ; the distance between the edges and midribs being now only half what it was at first. The incurvation increased sJightly during the next 4~ hrs., but remained nearly the same for the next 17 hrs. 30m. In 35 hrs. from the time when the sponges were placed on the leaves, the margins were a little unfolded-to a greater degree in the younger than in the older leaf. The latter was not quite unfolded until the third day, and now both bits of sponge were left at the distance of ·1 of an inch (2·54 mm.) from the edges; or about a quarter of the distance between the edge and midrib. A third bit of sponge adhered to the edge, and, as the margin unfolded, was dragged backwards, into its original position. |