. Electro-physiology. Electrophysiology. VI ELECTROMOTIVE ACTION IN VEGETABLE CELLS. Fio. 14(5. shock (O'l sec. after liberating the pendulum); opening K2 un- bridged the galvanometer circuit, which was broken, finally, by opening K3. The distance between Kl and K2, as also between K2 and K3, is variable. We shall return later to the results of these experiments; here it is sufficient to note that Burdon- Sanderson, with the help of the compensat- ing method, determined the of the first phase at about O'OS Dan., while that of the second did not exceed 0-82 Dan. If one or other half of t
. Electro-physiology. Electrophysiology. VI ELECTROMOTIVE ACTION IN VEGETABLE CELLS. Fio. 14(5. shock (O'l sec. after liberating the pendulum); opening K2 un- bridged the galvanometer circuit, which was broken, finally, by opening K3. The distance between Kl and K2, as also between K2 and K3, is variable. We shall return later to the results of these experiments; here it is sufficient to note that Burdon- Sanderson, with the help of the compensat- ing method, determined the of the first phase at about O'OS Dan., while that of the second did not exceed 0-82 Dan. If one or other half of the leaf is excited by break induction shocks (the electrodes being usually applied, as in Fig. 143, to opposite and approximately central points of the two leaf-surfaces), the coils of the induction apparatus must be pushed tolerably close (about 10 cm.) before an effect is produced. The direction of the induced current is by no means immaterial, since the effect appears much sooner when the current flows from upper to under surface than in the opposite case. The same applies to battery currents also. If a current, of moderate strength, adequate for excitation, is sent transversely through one half of the leaf in the direction of upper to lower (ingoing), it will be found on leading off from the other half that an excitatory variation of the leaf-current occurs, as a rule, at closure only. Stronger currents (1 Dan. to 2 Groves), on the contrary, excite on opening also, and with a long closure (30 sec.) produce as the visible sign of persistent excitation a whole series of oscillations of the leaf-current, which occur at irregular intervals during the passage of the current. Summation of stimuli may also be demonstrated in the Dioncca leaf, if stimuli (break induction shocks) are used of such low intensity that a single shock is inadequate to produce an effect, the interval between the stimuli being less than 0'4 sec. At 0'5 sec. the result becomes uncertain. This applies both t
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