Fig. 48.—Stimulating Action of very dilute KOH
So we see that, judged by the final criterion of the effect produced by anæsthetics and poisons, the plant response fulfils the test of vital phenomenon. In previous chapters we have found that in the matter of response by negative variation, of the presence or absence of fatigue, of the relation between stimulus and response, of modification of response by high and low temperatures, and even in the matter of occasional abnormal variations such as positive response in a modified tissue, they were strictly correspondent to similar phenomena in animal tissues. The remaining test, of the influence of chemical reagents, having now been applied, a complete parallelism may be held to have been established between plant response on the one hand, and that of animal tissue on the other.
Fig. 49.—Nearly Complete Abolition of Response by Strong KOH
The two vertical lines are galvanometer deflections due to ·1 volt, before and after the application of reagent. It will be noticed that the total resistance remains unchanged.
CHAPTER X
RESPONSE IN METALS
- Is response found in inorganic substances?
- —Experiment on tin, block method
- —Anomalies of existing terminology
- —Response by method of depression
- —Response by method of exaltation.
We have now seen that the electrical sign of life is not confined to animals, but is also found in plants. And we have seen how electrical response serves as an index to the vital activity of the plant, how with the arrest of this vital activity electrical response is also arrested temporarily, as in the case amongst others of anæsthetic action, and permanently, for instance under the action of poisons. Thus living tissues—both animal and vegetable—may pass from a responsive to an irresponsive condition, from which latter there may or may not be subsequent revival.