Fig. 16. (Pinguicula vulgaris.) Outline of leaf, with right margin inflected against two square bits of meat.

Experiment 7.—­A bit of meat was placed close to the incurved edge of a rather young leaf, and after it had re-expanded, the bit was left lying .11 of an inch (2.795 mm.) from the edge.  The distance from the edge to the midrib of the fully expanded leaf was .35 of an inch (8.89 mm.); so that the bit had been pushed inwards and across nearly one-third of its semi-diameter.

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 measured.  After 1 hr. 17 m. 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 slightly during the next 4 1/2 hrs., but remained nearly the same for the next 17 hrs. 30 m.  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. [page 374]

Experiment 9.—­A chain of fibres of roast meat, as thin as bristles and moistened with saliva, were placed down one whole side, close to the narrow, naturally incurved edge of a leaf.  In 3 hrs. this side was greatly incurved along its whole length, and after 8 hrs. formed a cylinder, about 1/20 of an inch (1.27 mm) in diameter, quite concealing the meat.  This cylinder remained closed for 32 hrs., but after 48 hrs. was half unfolded, and in 72 hrs. was as open as the opposite margin where no meat had been placed.  As the thin fibres of meat were completely overlapped by the margin, they were not pushed at all inwards, across the blade.

Experiment 10.—­Six cabbage seeds, soaked for a night in water, were placed in a row close to the narrow incurved edge of a leaf.  We shall hereafter see that these seeds yield soluble matter to the glands.  In 2 hrs. 25 m. the margin was decidedly inflected; in 4 hrs. it extended over the seeds for about half their breadth, and in 7 hrs. over three-fourths of their breadth, forming a cylinder not quite closed along the inner side, and about .7 of an inch (1.778 mm.) in diameter.  After 24 hrs. the inflection had not increased, perhaps had decreased.  The glands which had been brought into contact with the upper surfaces of the seeds were now secreting freely.  In 36 hrs. from the time when the seeds were put on the leaf the margin had greatly, and after 48 hrs. had completely, re-expanded.  As the seeds were no longer held by the inflected margin, and as the secretion was beginning to fail, they rolled some way down the marginal channel.