IN THE MOTOR ORGANS OF LKAVES. 



11 



On the following day the drops of fluid on the axis, rachises and petioles had assumed 

 a dark-brown colour, which fact, as well as their entire absence from the surfaces of 

 the pinna?, showed that they were due to exudation and not to surface-condensation. 



Experiment V, — A shoot of Cassia sumatrana set as in the previous experiment. In 

 a little over an hour visible exudation had set in in the axis, rachises and petioles. At 

 this time there was no evidence of change of colour in the pinn:e, but they had in great 

 part assumed their nocturnal positions of depression, convergence, and rotation according 

 to their respective ages, and that the phenomenon was not a simple one of general 

 flaccidity was shown by the fact that in those leaves which, in introducing the shoot 

 into the chamber, had been reversed, the pinna;, in place of being depressed below the 

 ane of the petiole, were elevated above it. Ultimately general ilaccidity and discolour- 

 ation occurred, accompanied by conspicuous exudation of drops of fluid on the axis and 

 rachises. The discolouration and exudation were sharply limited to those portions of 

 the specimen which had been directly exposed to the chloroform, the base of the axis 

 and the lower part of the lowest petiole which had been protected by the luting remaining 

 quite green, tnrgid, and devoid of any drops of fluid. 



The phenomenon of free exudation on the surface of 



periment* 



presents itself only so long as the latter is young and has not yet become clothed by 



any corky 



other words, so long as there are stomatic orifices present pcrmitti 



of the escape of fluid from the dense tissue beneath. So long as it does occur, it is, 

 of course, simply a parallel to the general exudation occurring from the leaves of plants 

 like Kalanchoe under similar conditions. The fact of general loss of tnrgescenco through- 



out the leaves is, in the absence of soluble colouring materials and with the presence of 

 an extensive intercellular area, indicated only by the flaccidity and saturation of the 

 tissues; and the special value of this set of experiments lies in the demonstration afforded 

 by some of them that the capacities of the water- conducting system remain entirely 

 unaffected under conditions abolishing the turgescence of tissues in which the active 

 retention of fluid is dependent on the continuous exercise of protoplasmic function, and 

 that the action of anaesthetics like chloroform is a purely localised one, confined solely to 

 the protoplasts which are directly exposed to. it, and not leading to any propagation of 

 the depression or abolition of functional activity from the protoplasts so situated to 

 those which are protected from the direct action of the anaesthetic. 



The phenomena attending the action of anaesthetics on vegetable tissues are not 

 peculiar ; but, save in certain exceptional cases to be presently alluded to, occur 

 whenever protoplasmic function is depressed or abolished in tissuos whose turgescence is 

 dependent on the presence of living protoplasm. This comes out very clearly from the 

 results of the following experiments: 



Experiment I. — A leaf of Kalanchoe, weighing 12 9 grammes, was immersed for 

 about one minute in water at a temperature of 69^., and then gently wiped dry and 

 placed in a hermetically closed chamber. It soon began to exude drops of liquid, which 

 within three hours had accumulated in large pools, the colour of the leaf having at the 

 same time begun to show a yellowish tint. It now weighed 1 1*2 grammes, corresponding 

 to a loss of l-7c.c. of fluid. Discharge continued to occur, and on the following morning 



the weight was only 1<M grammes, indicating a loss of 2'oc.c. of fluid and \9'o per 



cent- of total weight. 



Aww. Roy. Box. Gaud. Caucuita Yol. VL 





