134 



BOTANY OF THE LIVING PLANT 



of growing organs, which are slow in action, and take their origin in 

 variations of the osmotic turgor of the hving cell, and of the resistance 



Fig. 94. 

 Whole fruit of Hura crepitans, before ruptiore of its woody carpels (after Le Maout.) 

 a, b, single carpels after the explosion, showing each coccus -with gaping halves. 

 The rupture happens suddenly, each coccus taking a wider shape ; the cocci and 

 seeds are thus thrown asunder. c = a single large seed. 



i 



Fig. 95- 



Fern sporangia : A, with the cells of the annulus darkly shaded, and curved 



strongly backwards by drying of its cells. B, the annulus after its sudden recovery, 



while the previous position is shown in dotted lines. C shows in detail cells of the 



annulus in A , and D shows similar cells in the state seen in B. See Chapter XXI. 



of the cell-wall that holds it in. All of these phenomena of movement 

 in growing parts play within the limits of turgor of the constituent 



