72 RESPONSE IN THE LIVING AND NON-LIVING 
of response. The immediate changes made in the 
response, in consequence of the application of chemical 
reagents, could then be demonstrated in a striking 
manner. And with a little trouble, specimens can be 
secured in which perfect regularity of response is found. 
The record given in fig. 16, obtained with a specimen 
of radish, shows how possible it is to secure plants in 
which response is absolutely regular. I subjected this 
to uniform stimulation at intervals of one minute, dur- 
ing half an hour, without detecting the least variation 
Nerve : 
yg 

Before ap After 
Fic. 43.—Errecr of CHLOROFORM ON NERVE Response (WALLER) 
in the responses. But it is of course easier to find 
others in which the responses as a whole may be taken 
as regular, though there may be slght rhythmic 
fluctuations. And even in these cases the effect of 
reagents is too marked and sudden to escape notice. 
For the obtaining of constant and strong response I 
found the best materials to be carrot and radish, selected 
individuals from which gave most satisfactory results. 
The carrots were at their best in August and September, 
