52 RESPONSE IN THE LIVING AND NON-LIVING 
vreat. When the stimulus is carried beyond moderate 
limits, the response, owing to fatigue or other causes, 
may Sometimes undergo an actual diminution. 

















| 2 4 16 1820 22 24 26 2830 3234363840 
Fia. 30.—CurvES SHOWING THE RELATION BETWEEN THE INTENSITY OF 
STIMULUS AND RESPONSE 
Absciss indicate increasing intensity of stimulus. Ordinates indicate magni- 
tude of response. ( Waller.) 
I have obtained very interesting results, with 
reference to the relation between stimulus and response, 

Fic. 31 
Taps of increasing strength 
1:2:3:4 producing in- 
creased response in leaf- 
stalk of turnip. 
jwhen experimenting with plants. 
These results are suggestive of 
various types of response met 
with in animal tissues. 
1. In order to obtain the 
simplest type of effects, not com- 
plicated by secondary phenomena, 
one has to choose specimens which 
exhibit little fatigue. Having pro- 
cured these, I undertook two series 
of experiments. In the first (4) the stimulus was applied 
by means of the spring-tapper, and in the second (5) by 
torsional vibration. 
