71 
CHAPTER IX 
PLANT RESPONSE 

EFFECT OF ANASTHETICS AND POISONS 
Effect of anesthetics, a test of vital character of response—Effect of chloro- 
form—FEffect of chloral—Effect of formalin—Method in which re- 
sponse is unaffected by variation of resistance—Advantage of block 
method—Effect of dose. 
THE most important test by which vital phenomena are 
distinguished is the influence on response of narcotics 
and poisons. For example, a nerve when narcotised 
by chloroform exhibits a diminishing response as the 
action of the anesthetic proceeds. (See below, fig. 43.) 
Similarly, various poisons have the effect of permanently 
abolishing all response. Thus a nerve is killed by 
strong alkalis and strong acids. I have already shown 
how plants which previously gave strong response did 
not, after application of an anesthetic or poison, 
give any response at all. In these cases it was the last 
stage only that could be observed. * But it appeared 
important to be able to trace the growing effect of 
anesthetisation or poisoning throughout the process. 
There were, however, two conditions which it at first 
appeared difficult to meet. First it was necessary to 
find a specimen which would normally exhibit no 
fatigue, and give rise for a long time to a uniform series 
