54 



THE PHYSIOLOGY OF STOMATA. 



In 20 minutes the rate of transpiration increased fourfold, with little or no 

 change in the size of the stomata. The behavior of these organs is apparently- 

 anomalous in this instance. It is certainly surprising to find that some of 

 them remain so widely open after 7 hours' darkness.* 



Experiment 74.— July 21, 1904 (fig. 18). Oeotillo. Burette potometer; plant used in 

 experiment 69, July 20; placed in dark room at io h 3o m p.m., July 20, and no records 

 taken till 6 h 3o m a. m.. July 21, plant remaining in dark room till i2 h 40 m , then placed 

 in light till i2 h 55 m ; replaced in dark till 1 p. m. 



Table 32. — Rates of transpiration. 



6cc 



7p.m. 

 Fig. 18. 



3a-m-. 



7a.m. 



Ila.rn. 



3p.m. 



1 1 p.m. 



-Curves for experiments 74 and 151. Fouquieria splendens. The dot-and-dash 

 curves are of stomatal movement. 



*I have later (Dec, 1906) found the stomata in a verbena kept in total darkness for 48 

 hours (2) 4 to 6 micra open. 



