144 C08VIBGHAM ON FLUCTUATIONS IX TUEGESCEXCE. 



pinnules, suoceeded in one instance by deep and in another by slight depression of the primary petiole 



of the injured leaf. 



In this experiment we have evidence of the extent to which excessive rcot-supply may serve to 



discount the result nominally attending the presence of active transpiratory loss connected with moderate 

 tttmospheric humidity. 



.— I! esults following the application of heat to points in the course of mature axes. 



Experiment LIX. — Hat applied by focusing the rays of the sun upon a point in an axis 4 inches from 

 the I* of next above it, anil about 075 of an inch from the one next beneath it. — Centrifugally propagated 

 action ocourred in all the eleven leaves situated on the distal side of the point of application. No 

 mt ion whatever occurred in any leaves on the basal side. 



■ 



Experiment LX. — Centrifugally propagated action in all the leaves situated to the distal side 



of the point of application. 



Kxri RiMi.vr LX1.~ Centrifugally propagated action in all the leaves situated beyond the point 



of application. 



If we insist in regarding the movements which the leaves of Mimosa pudica exhibit under the 

 influence of textural injuries or meohanicai disturbauce as necessarily dependent on stimulation and 

 active contraction of the protoplasts of the motor organs, the results of this entire series of experiments 

 must force us to the conclusion that the degree of irritability in the tissues is almost entirely regulated 

 by the nature of the hygrometric 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 hygrometric conditions might exist, 

 but there is certainly nothing to explain why it should do so. But if we regard the movements as 

 having no direot 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 theory can 



readily do so; and this being so, there can be 



eases 



has here, as in many other 



APPENDIX F. 



OX THE EFFECTS WHICH FOLLOW THE LOCAL APPLICATION OF HEAT TO AREAS IN THF 



COURSE OF AXES OF MlMOSA PUDICA. 



As has been pointed out in the body of this paper, the effects following the loeal application of 



in the case of young, soft, green 



points in the course of axes of Mimosa 



shoots from 



mature, woody ones. In both 



propagation of movement » constant; but in the former case centripetal propagation frequently occurs 

 to a certam extent, whilst in the latter it is entirely absent, save in cases wherler the S^^Z 



Z Zl, ^r nedia * n T h , b ° Urh00d ° f th ! ** W bel - *> «* ^en is confined to theater. 



ihe following data are derived from a series of experiments on mature shoots in which heating was 

 in some cases effected by means of the application of an o™n fl,™ ;„ ^ . T , g ™ 



application of an 



^ u«, appuuauuu oi an open flame, in others by the employment of 

 by focussing the sun's rays by means of a lens •— 



a. 



•Effects following application of an open fli 



riment 1.— Flame applied 



beneat li 



beyond 



Experiment ll-Ftame applied as in the preceding «w._Aotion as ab 



