30 



CIKCUMNUTATION OF SEEDLINGS. Chap. I. 



abruptly, then made a small loop and then a larger zigzag 

 curve. During the night and till 11a.m. on the following 



Fig. 20. 



Vicia faba: circumnutation of a radicle, at first pointing verti.'ally up- 

 wards, kept in darkness, traced on a horizontal glass, during 14 hours. 

 Movement of bead of filament magnified 23 times, here reduced to 

 one-half of original scale. 



morning, the bead moved to a great distance in a nearly straight 

 line, in the direction indicated by the broken line in the figure. 

 This resulted from the tip bending quickly downwards, as it 

 had now become much declined, and had thus gained a position 

 tiighly favourable for the action of geotropism. 



Fig. 21. 



D. 



K 



Cicia faba : tracks left on inclined smoked glass-plates, by tips of radicles 

 in growing downwards. Plate C was inclined at 63°, plates A and D 

 at 71°, plate B at 75°, and plate E at a few degrees beneath the 

 horizon. 



