75004434.htm

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Scientific Memoirs by

TABLE XII.—Showing Results of section of Distal Pinnules in young
heavy Leaves.

No. of Experi- ment.	Result.
1	Action in the cut pinnules; pause; action in the primary pulvinus; pause; action in the pinnules of that pinna; no further result.
2	Action in the cut pinnules; pause; violent and extreme action in the primary pulvinus; pause; centripetal action in one or two distalpinnules of the cut pinna; no further result.
	The other pinnules responded readily to mechanical impulses.
3	Action in the cut pinnules; pause; action in the primary pulvinus; spreading, centripetal action in the cut pinna; pause; nearly complete; action in the other distal pinna; no further result.
4	Action in the cut pinnules; pause; progressive action in the 'cut pinna; pause; action in the remaining pinnæ; action in the primary pulvinus.
5	Action in that pinna only.
6	Pause; action in the primary pulvinus; action in the distal two-thirds of the cut pinna; pause; action in the basal third; no further result.
7	Pause; action in the primary pulvinus; action in the pinnules of that pinna; no further result.
8	Results as in No. 7.
9	Ditto.
10	Ditto.

This table illustrates two points very clearly"the discontinuity of action
under certain conditions, and the limitation of action under the influence
of others. All these experiments were conducted between 7 and 8 o'clock of
a warm, moist, still morning, on leaves which had not yet been exposed to direct
sunshine and which were loaded with moisture. They were all large, young
leaves, and in the majority of cases the weight of the pinnæ obviously strained
on the primary pulvinus. Under these conditions there was a special reason
why any loss of fluid should tell with special effect on the primary pulvinus,
and at the same time a reason for only limited loss of fluid. The result ought
to be specially rapid action in the primary pulvini and only limited action else-
where, and such results were actually present, as the table shows.