XLVI. -DIURNAL MOVEMENTS IN PLANTS 



By 



Sir J. C. BosE. 



The subject has lonw been a perplexing one, and its 

 literature is copious. After a good many years of experi- 

 mental investigation, I have succeeded in analysing the 

 main factors concerned in the many phenomena which 

 have been described as Nyctitropism. The results of the 

 researches are given in a sequence of five papers, which 

 may be read separately, yet will be seen as so many 

 chapters of what has been a single though varied investiga- 

 tion. 



The different chapters are : 



1. Daily movements in ralation to Light and Dark- 



ness. 



2. Daily movements due to Variation of Tempera- 



ture affecting Growth, 



3. Daily movements due to Variation of Temperature 



affecting Geotropic Curvature. 



4. The Immediate and After-effect of Light. 



5. Diurnal Movement of the leaf of Mimosa due 



to combined effects of various factors. 



Nyctitropic movements are thus described by Jost* : 



"Many plant organs, especially foliage and floral leaves 

 take up, towards evening, positions other than those they 

 occupy by day. Petals and perianth leaves, for example, 

 bend outwards by day so as to open the flower, and inwards 

 at night so as to close it . . . Many foliage leaves also 

 may be said to exhibit opening and closing movements, not 



* Jost— /6i</, p. 500. 



