300 MACDOUGAL AND SPOEHR— GROWTH AND IMBIBITION. 



21-25, 1916. Current was now turned on an electric heater, July 

 25, 10 A.jNL, and the Opimtia reached 25° C. about 6 P.M. 



July 21, ipi6: 4:30 P.M. — A growth of nearly 3 mm. had oc- 

 curred in the previous 24 hours at a temperature of 24° C. and 



25° c. 



28, II :oo A.M. Growth during the previous 18.5 hours was at 

 rate of 3.6 mm. per day, 25° C. 3:00 P.M. Growth for previous 

 4 hours was at rate of 3.9 mm. per day, 25° C. 



Current off and plant cooled to 18° C. at midnight — in 9 hours. 



2p, 8:00 A.M. Growth during previous 8 hours was at rate of 

 3.3 mm. per day at 18° C. 10:00 A.M. Growth of .2 mm. in 2 

 hours was at rate of 2.4 mm. per day, 18-17° C, which was double 

 the rate displayed at the same temperature before being heated. 

 4:00 P.M. Growth at rate of 2 mm. daily during previous 6 hours 

 at 19° C. 



50, 7 :oo A.M. Growth during previous ten hours was at rate 

 of 2.4 mm. daily at 19° C. 



5/, 7 :oo A.M. Growth of 2.4 mm. during previous 24 hours at 

 18° C. 



Aug. I, 6:30 A.M. Growth in previous 19 hours was at rate 

 of 2.6 mm. daily, at 18-19° C. 



The plant failing to return to the initial rate of about i mm. 

 daily, the heater was again put in action and the plant had a 

 temperature of 28° C. at 11 A.M. Growth during this rise of 

 9° C. in 4.5 hours was i mm. or at rate of about 5.4 mm. daily. 



The temperature was held constant to within a degree but the 

 rate was 6 mm. daily during the first 6 hours, then 7.2 mm. per day 

 during the next 3.5 hours. 



2, 8 :oo A.M. Growth at rate of 8.04 mm. per day during previ- 

 ous 1 1.5 hours at 28° C. 2:00 P.M. Rate during previous 5 hours 

 10.8 mm. daily at 27-28° C. 4:00 P.M. Rate during previous 2 

 hours 12 mm. daily at 28° C. 9:00 P.M. Rate 9 mm. daily during 

 previous 5 hours. 



Heat was now cut off and the temperature fell to 16° C. in 4 

 hours. 



5, 8:00 A.M. Rate of 2.9 mm. daily during previous 7 hours at 



