COKKIKGIIAM OiC FLOCTUATIOXS IN TUUGESCENCE.
1 one iustance by deep an pinnules, Buoceeded : d in another by slight depression of the primary ;
of the iujuied leaf.
l u this experiment we have evidence of tlie extent to which exoesaive rcot-supply may serve to
discount the result nominally attending the presence of active transpiratory loss eonneotad with moderate
Dtmospherio humidity.
c.—Uemlh following the application of heat io points in the course of mature azes.
Expkkiment ZJX.—Hiai applied by foeusslng ihe rays of the sun upon a point in an a.m 4 iiicAcs from
the leaf next above it, and about 0'75 of an inch from the one nnxt Icncatk it.—Centrifugally propagated
action occurred in all the eleven leaves situnted on the distal side of the point of application. No
action whatever occurred in any leaves on the basai side.
Expebdikst LX.—Centrifugally propagated action in all the leaves situated to the distal side
of the point of application.
Exi'eiiimest LXI.—Centrifugally propagated action in all the leaves situated beyond the point
of application.
If we insist in regarding the movements which the leaves of Mimoin pudica exhibit under the
influence of textural iajiaries or mechanical disturbance as necessiriiy dependent on stimulation and
active eontroction of the protoplasts of the motor organs, the results of this entire series of experiments
must foi-oe us to the conclusion that the degree of irritability in the tissues is almost entirely regulated
by the nature of the hygrométrie conditions to which the plants are exposed, and runs parallel with the
extent to which defective supply or excessive loss of water is present. It is, of course, possible to
imagine that such a relation between protoplasmic irritability and hygrométrie conditions might exist,
but there is certainly nothing to explain why it should do so. But if we regard tha movements as
having no direct relation to functional activity, but as directly dependent on purely physical processes of
redistribution of liquid throughout the tissues, it at onco becomes evident that the presence of any
external conditions favouring the occurrence of rapid disturbances in liquid equilibrium must necessarily
also favour the occurrence of rapid movements. The series of coincidences is of such a nature that,
whilst the ordinarily accepted theory is quite incapable of accounting for it, the physical tiieory cnn
readily do so; and this being so, there can be no question that the latter has here, as in many other
cases, the better claim to a
APPENDIX F.
As has been pointed out in the body of this paper, the effects following the local application of
heat to points in the course of axes of Mimow pudiea are different in the case of young, soft, greeu
shoots from those which present themselves in mature, woody ones. In both cases extensive centrifugal
propagation of movement is constant; but in the former case centripetal propagation frequently occurs
to a certain extent, whilst in the latter it is entirely absent, save in eases wherever the point of application
is in the immediate neighbourhood of the first Iraf below it, and then is conBned to the latter.
The following data aie derived from a series of experiments oa mature shoots in which heating wa9
in some cases effected by means of the application of an open flame, in others by the employment of
heated forceps, and in still others by focussing the sno's rays by means of a lens:—
a.—Effects following application of an open flame.
Espeuimext I.—Flame applied midway beticeen two leaves.—Action i
of application; no action whatever beneath it.
Experiml-NT II.—Flame applied as in Ihe preceding cajt.—Action a:
1 all the leaves beyond the point
above.
t
APPENDICES. 145
r I I I , Flame appUed near the iiifeiior leaf and at a considerable distance from the superior
one.—Action in all the leaves beyond tho point of application; no action in any beneath it.
Experimest I^.—Flame a2iplied immediately above the inferior leaf and far frcm Ike superior one.—
Action in all the leaves beyond the point of application, and in the leaf immediately' beneath it.
h.—Infects following the searing of a point in the course of an axis with strongly heated forceps.
Experiment Y. Forceps applied to the axis clone hyond an inferior leaf and far from the next
superior one.- Progressive centrifugal action of all the leaves along the course of the axis beyond the
point of application; no action beneath the point of application.
Experiments VI, Y I I , V l l i , IX, X.—Procedure and results identical with those of experiment V.
ExPEniMENT ni-Forceps applied immediately above tJie inferior lcaf.-Ko.tion in the first leaf
beneath the point of application and In all those above it.
I n a series of thirty similar experiments in which complete movements occurred in all the leaves
on the axis beyond the point of application, movements occurred in the first leaf beneath it in only
five instances, and in all of these the point of application was very close to the origin of the primary
petiole from the axis.
c.—Efects following focussing the rays of the sun on a given point i Î of a
he leaf beneath and about /wo inches from the
. all the lea"\'e3 above the point of applica-
Experiment XH.—ibc(T/ p'tnt close to the origin of t
one next above íí.—Complete, spreading, centrifugal action in
tion I no action whatever in any leaf beneath it.
Experiment XIII.—Foen/ point close to the origin of the leaf hcnrath and about three inches from
the one next above ¿¿.—Complete action in all the leaves beyond the site of application; no action whatever
in any leaf beneath it.
Expebiment XIV.—Fo«7? point close io the origin of the leaf beneath it and about an inch and c half
from the one next above jí.—Complete action in all the distally situated leaves; action in the leaf immediately
beneath the site of application.
Expekiuent XN.—Focal point about midtcay between the leares beneath and above Action in all
the nine leaves situated distally; no action whatever in any leaf beneath the point of application.
E x p e r u i k n t XYI.—Focnl poiut close to the origin of the leaf beneath it and ahout thirteen inches from
the first one abote ¡í.—Action in all four leaves situated distally; action in the leaf immediately beneath
the point of application.
I n a series of nineteen experiments of this nature, in which movements occurred either in all the
distally situated leaves or in a considerable number of them, action only occurred beneath tlie point of
application in five instances, and in all of these the point of application was very olose to the origin of
the petiole of the leaf next beneath it and movements were confined to the latter only.
As haa already been pointed out in Appendix E, the results following the local application of heat
to points in the course of an axis vary according to the conditions of atmospheric and telluric humidity
prevailing at the time of experiment. "When, as in tlie case of the experiments detailed above, humidity
is moderate or low, the application is foUowed by very extensive centrifugal propagation of movements,
extending frequently along the whole of the distal portion of the axis; but where this is no longer the
ease, propagation diminishes in extent and completeness; and where humidity attains maximal proportions,
it may be atlended by an entii'o absence i.f any appreciable movements whatever.
Expkrimbnt XVII.—The points of a paii' of strongly-heated forceps were applied to an axis just
after a heavy fall of rain. Spreading centrifugal action occurred in all the distally situated leaves, but
the action was incomplete; for, whilst the primary petíoles became deeply depressed, the pinnse aud
pinnules showed only very slight displacements,
Exfekiment X T I I I . - J u l y 20th, 8 a.m. Atmospheric temperature SO'S^J". Humidity 95 per cení.
Heavy rain had fallen during the course of the precious night; rain zeas still filling gently at the time of
experiment, and everything teas drenched xcith »¡t>!íi¿íífí.—The tips of a strongly heated pair of forceps were