Circumnutatio?i of Some Flowering Plants. 67 



in producing the accelerated movements, as compared with 

 those obtained by Darwin. 



Convolvulus Septum. — Young actively growing shoots of 

 this species were observed in the greenhouses of the Botanic 

 Garden for four days and nights by members of the class in 

 continuous relays. Note was made of the temperature of the 

 house, and of the prevailing atmospheric conditions outside. 



A dark sky and low temperature (15 C.-19.5 C.) gave dis- 

 couraging figures for the first three days. The quickest time 

 made during the period was i hour 45 minutes ; the longest, 

 4 hours 15 minutes; average, 2 hours 40 minutes. The 

 twenty-fifth of the month was a clear day and the temperature 

 ranged from 15.5 C. to 33.5 C, resulting once in a circumnu- 

 tation in 57 minutes: the longest took 3 hours; the average 

 time for the day was i hour 53 i^; minutes. The behavior of 

 the plants with respect to light and temperature would point 

 to Darwin's conclusion, that both are important factors in plant 

 movement. 



The rainy days afforded no good opportunity for observa- 

 tion of periodicity of growth, but the clear day caused an 

 acceleration of movement from 8.05 a. m. till 2.30 p. m. in 

 one ea.se, and from 9 a. m. till 4.32 p. m. in another, the suc- 

 cessive circles being : 



Specimen 1. 



First circle 2 hours 30 minutes. 



Second circle 1 hour 45 " 



Third circle 1 " 35 " 



Specimen 2. 



First circle 2 hours. 



Second circle I hour 50 minutes. 



Third circle 1 " 15 " 



Fourth circle I " 10 " 



Fifth circle 1 " 2 " 



Sixth circle c-j " 



The night circumnutations were longer than the average 



daily ones. 



