PERIODICAL OPENING AND CLOSING OF FLOWERS. 



The time, therefore, varies from ten to twenty hours, the mean 

 being somewhat above fourteen, those hours only being reckoned 

 in which the phase is less than the mean of the whole day. 



The species observed afford the subjoined results according 

 to the difference of the hour at which the plants awake from their 

 sleep, or reach the mean daily phase. 



Number of species. 

 Ipoincea purpurea . 



Passiflora coerulea . . 

 Pyrethrum corymbosum 

 CEuothera biennis . . 

 Lychnis vespertina 



1 



2 



4 



8 



11 



23 



21 



7 



2 



1 



1 



1 



1 



Hour of waking. 



2 A.M. 



3 „ 



4 „ 



5 „ 



6 „ 



7 ., 



8 „ 



9 » 

 10 „ 

 12 



2 P.M. 



6 n 



7 „ 



Though there seems to be no time of the day when the blossoms 

 of certain plants cannot open, yet in the greater number of cases 

 they are closed soon after sunset ; the number of species increases 

 at first slowly, then more rapidly from 2 a.m. to 7 a.m., and then 

 decreases again rapidly till midday. After that hour, only those 

 species open which are night-bloomers. 



With the exception of a few hours about midnight, there is on 



