:U0 LIFE MOVEMENTS IN PLANTS 



Vtiriatiou of temperature. The Therinonastic Recorder em- 

 ployed in this investigation is showti in figure 110. The 

 record given in figure 111 shows that the perianih seg- 

 ment, subjected to a few degrees' rise of temperature, 

 responded by an up-movement of closure, due to greater 

 expansion of the outer lialf. The latent period was 6 

 seconds, and the maximum etlect was attained in the 

 further course of 21 seconds, Tliis experiment shows that 

 the thermonastic response ot this flower is of the negative 

 type. 



Effect of stifHiilus : Experiment 116. — In the positive 

 type of thermonastic organs, where rise of temperature 

 induced a movement of opening, stimulus induced the oppo- 

 site movement of closure (Expt. 114). We shall now study 

 the effect of stimulus on the movement of Nymphcea, 

 which undergoes closure during rise of temperature, as seen 



Fig. 111. — ]?<egative thermonastic response of Nympku-a. Ajipliiation of 

 warmth at the vertical mark induced up-movement of closure but stimulus of 

 electric shock at arrow induced rapid excitatory down movement of opening. 

 Successive dot.* .at intervals of a second. 



in the first part of the record in figure 111. Stimulus of 

 electric shock was applied at the point marked with an 



