blown into the closed chamber containing the plant. It will be seen how rapidly chloroform produced depression of response which afterwards culminated with death and abolition of response (fig. 91).
Exactly similar effects were obtained with chloral, also with formalin. These were applied in the form of solution on the tissue at the two leading contacts.
It has been shown that the electric response is a faithful index of physiological action and that such a response is given by all plants and by their different organs. It has also been shown that in the matters of response by induced galvanometric negativity, of modification of response by high and low temperatures, they are strictly correspondent to similar phenomena in muscle and nerve. Judged by the final criterion of the effect produced by anæsthetics and poisons, these electric responses in plants fulfil with animal tissues the test of vital phenomenon.
The electro-physiological investigation on plants will undoubtedly throw much light on the response phenomena in the animal. With animal tissues, experiments have to be carried on under many great and unavoidable difficulties. The isolated tissue, for example, is subject to unknown changes inseparable from the approach of death. Plants, however, offer a great advantage in this respect, for they maintain their vitality unimpaired during a very great length of time. In animal tissues, again, the vital conditions themselves are highly complex. The essential factors which modify response can, therefore, be better determined under the simpler conditions which obtain in plant life.
