AUTONOMIC MOVEMENTS IN SUCCULENTS 



303 



Preliminary experiments, which will not be recorded here, 

 gave some evidence that the short period movements are con- 

 trolled by temperature, light, the water-content of soil and of 

 tissues, both at the time of the experiment and previously, and 

 possibly also by the evaporative power of the air. Conse- 

 quently, movements have been measured under various environ- 

 mental conditions and a record kept of these conditions. In 



TABLE 2 

 Experiment 1. Movements of three branches of Plant No. 4 



TABLE 3 



Experiment 2. Movements of Plant No. 



Mar. 11 9 a.m. to 10 a.m.. 



10 a.m. to 11 a.m.. 



11 a.m. to 12 noon 



12 noon to 4 p.m. 

 4 p.m. to 7 p.m. 

 7 p.m. to 



Mar. 12 7 a.m.. 



7 a.m. to 10 a.m.. 



10 a.m. to 12 noon 



12 noon to 4 p.m. 



+0.1 

 +0.1 

 +0.6 

 +0.7 

 0.0 



-0.9 

 +0.5 

 +0.9 

 +2.9 



experiments 1-6, the normal range of day and night temperatures 

 and light have been used with a variation in the water-content 

 of soil and tissues. In experiment 7, the light and temperature 

 changes are still the normal ones but the plants are exposed to 

 different wind velocities and hence to different evaporative 

 intensities. Experiment 8 covers various conditions of light 

 and temperature changes with the water-content of soil and tis- 

 sues remaining as nearly constant as possible. 



