20 RESPONSE IN THE LIVING AND NON-LIVING 



deflection of 1 mm. at a distance of 1 metre. For a 

 quick and accurate method of obtaining the records, I 

 devised the following form of response recorder. The 

 curves are obtained directly, by tracing the excursion of 

 the galvanometer spot of light on a revolving drum 

 (fig. 8). The drum, on which is wrapped the paper for 

 receiving the record, is driven by clockwork. Different 

 speeds of revolution can be given to it by adjustment of 



FIG. 7. RECORD OF RESPONSES IN PLANT (LEAF-STALK OF CAULIFLOWER) 

 BY METHOD OF NEGATIVE VARIATION 



The first three records are for stimulus intensity 1 ; the next six are for in- 

 tensity twice as strong; the successive responses exhibit fatigue. The 

 vertical line to the left represents '1 volt. The record is to be read from 

 right to left. 



the clock-governor, or by changing the size of the driving- 

 wheel. The galvanometer spot is thrown down on 

 the drum by the inclined mirror M. The galvanometer 

 deflection takes place at right angles to the motion of the 

 paper. A stylographic pen attached to a carrier rests on 

 the writing surface. The carrier slides over a rod parallel 

 to the drum. As has been said before, the galvano- 

 meter deflection takes place parallel to the drum, and 



