Amphicarpoea monoica. 297 



beginning earlier and continuing until 4 or perhaps 4.30 

 P.M., if the day is very hot. 



The quickest rate obtained was 51 minutes; the longest 

 3 hours 36 minutes. In the former ease, the specimen was 

 unsupported and was 14 inches high. It was observed 

 upon February 8, the temperature being 26]/,° C.; it com- 

 pleted a circle 7^4 inches in diameter between 1 1.42 a.m. 

 and 12.33 PM - In the latter case the specimen was 9 

 inches high. The observation was made upon June 30 

 between 1.32 a.m., and 5.08 a.m. The temperature was 

 i6°-i4° C., and the circle but 2}< inches in diameter. 

 Both days were bright and clear. 



It is true that the smaller plant had not yet exhibited a 

 twining inclination. But from the two extremes may be 

 gained some idea of the varying conditions under which 

 these experiments with Amphicarpcea have been performed. 

 From what I have observed, I am confident that so long a 

 time would not have been recpiired by the second plant, 

 had the records been made under conditions similar to those 

 of the first. It may be best, therefore, to state the longest 

 time noted for an unsupported plant whose height was 

 twelve or fourteen inches. 



A plant, 14 inches high on February 14, completed a 

 circle from 6 p.m. to 8.15 p.m., temperature 21 C. The 

 time was 2 hours 15 minutes. On July 2, another specimen 

 12 inches high, completed a circle in 2 hours and 10 

 minutes, the temperature being 23 C. The time of day was 

 6.35 p.m. to 8.45 p. M. 



The series which follows is selected as showing average 

 rates of circumnutation and also the periodicity to which al- 

 lusion has been made. The specimen was 22 inches high, and 

 supported, 9 inches being free; the observations were made 

 during February. Beginning at 9.30 a.m., a circle was 

 completed in 1 hour and 20 minutes ; another immediately 

 followed and was completed at 12.01 p. m., in 1 hour and 

 10 minutes. An interval of a few moments unfortunately 

 occurred ; at 12.30 p.m., it was placed in position again, and 



