CHAPTER VII. 



CURVATURES. 



Section A. Geotropism. 



Section B. Decapitation eocperiments, curvatures due to in- 

 jury, to contact, to unequal turgidity, to 

 Jla^ddity. 



Section C. Heliotropism. 



Section D. Diaheliotropism, Diageotropism, epinasty, nuta- 

 tion of epicotyls. 



Section A. Greotropism. 



(19)1) Region of cwrvature coincides with region of 

 growth, (roots.) 



If the curvature is to be observed in damp air a bean- 

 root of not more than 15 mm. in length answers best. 

 It should be marked at intervals of 2 mm. and pinned to 

 the lid of a stoppered jar half full of water ; the jar should 

 be occasionally inverted for' a moment or two so as to 

 thoroughly wet the seedling and the cork. After 12 

 hours measure the distance between the marks, which 

 gives the region of greatest gro\vth, and note the 



