VARIATION OF TENSION 



241 



perature. The possibility of the influence of other factors 

 in the diurnal movement will now be considered. 



Fig. 140. Diurnal record of adult leaves of Dahlia, Papaya, 



and Croton. 



Diurnal Variation of Tension and Bulk in 



Different Organs 



Kraus found that the tissue-tension of a shoot exhibits 

 a daily periodicity under normal alternation of day and 

 night. The tension diminishes throughout the day as the 



