INDUCED RHYTHM IN TRANSPIRATION. 



67 



The rate commenced to increase shortly after 1 a. m. and rose to an early 

 morning maximum at 6 a. m., July 19. 



llajn. 1p.m. 3 5 7 9 II 1a.m. 3 5 7 9 II 



Fig. 21. — -Curve for experiment 56. Fouquieria splendens. The temperature during the 

 experiment.is shown by the broken line. 



Experiments 58, 59, and 60. — July 18-19, 1904 (fig. 22). Set up at 5 p. m. ; on labora- 

 tory porch till 1 p. m., then placed in dark room, of which temperature was 32.5°C.,the 

 same as without; dark room remained open until 3 a. m., when it was closed; no 

 variation at this time (32. 5 C.) until close of experimentation. 



Experiments 62, 63, and 64 (fig. 23) were conducted simultaneously with the above, but 

 remained without on laboratory porch till 3 a. m. 



Experiments 65 and 66 (controls) were identical with the foregoing in all respects, but were 

 ahowed to remain on laboratory porch under normal diffused illumination. 



Note. — The maxima occurring in experiments 58 to 60, 62 to 64, at 1 p. m., toward the 

 close of the experiment, were due to brief exposures to light. 



Table 38. — Hourly rates 0} transpiration. 

 [The hourly rates given are derived by measurements of uncalibrated tube potometers.] 



Time. 



8 p. m 



9 p. m 



10 p. m 



11 p. m 

 1 a. m 

 3 a. m 



5 a. m. 



6 a. m 



7 a. m, 



8 a. m, 



9 a. m 



10 a. m 



11 a.m. 



12 day. 



1 p. 111 



2 p. m 



3 p. m 



4 p. m 



5 p. m 



No. 58. 



2.0 

 2.0 

 1-7 



i-7 

 2.0 

 3-2 

 7-4 

 8.7 

 7-3 

 7.0 

 6.0 

 4-9 

 4-4 

 3-9 

 3-5 

 2.9 

 8.0 

 ro.8 

 9-9 



1.8 



1.65 



i-5 



i-55 



1.6 



3-o 



5-6 



5-2 



4.0 



3-8 



3-4 

 2.7 

 2.2 

 i-9 

 1-9 

 i-7 

 50 



7-7 

 6.2 



No. 63. 



2.0 



1.8 



1.6 



i-7 



1-55 



1-5 



2-35 



2.5 



2.3 



2-4 



2. 1 



i-9 

 i-7 



1.6 

 2. 1 



3-8 

 5-6 

 5-5 



2.2 



1.8 



i-5 



i-5 



i-4 



115 



2. 1 



2.4 



2.2 



2.2 



1.8 



i-45 



1-35 



1 .2 



1.85 



i-75 



4.0 



5-6 



5-i 



Stomatal pores measured at 9 a. m., 2 to 6 micra wide in all; at I2 h i5 m p. m., 2 to 6 

 micra wide in all; at i2 h 45 m p. m., 2 to 6 micra wide in 64. 



