MECHANICAL RESrONSE TO STIMULUS 



21 



by attaching the leaf to the long arm of the recording Optic 



Lever, and shortening the distance of the recording surface. 



The records given in figs. 15 and 16 were automatically 



obtained by the impression of 



the moving spot of light on a 



sensitive film wrapped about 



the recording drum. The leaf 



was excited by a single strong 



induction-shock. In order to 



obtain the complete curve of 



response and recovery — the 



double process being aCCOm- FIG. 15. Photographic Record of 



plished in the course of about Response and Recovery of Mimosa, 



1 taken on a slowly moving drum. 



seven minutes — the first record Record shows actual movement 



. , , , . reduced to one-third. 



was taken on a slowly moving 



drum. For the detailed study of the characteristic time- 

 relations of the first part of the curve, again, two more 

 records were obtained, one with a moderate (fig. 15) and the 



Fig. 16. Photographic Record of Response in different specimen, taken 

 on a faster-moving drum, showing only first part of the curve. Each 

 division of time-scale = *5 second. 



other with a rapid speed of drum (fig. no). The last of 

 these enables us to obtain time-measurements which are 

 accurate to less than ^ of a second. The method by 



