500 



MODIFIED CIRCUMNUTATION. 



CHAP. X 



Fig. 186. protrude whilst the fol- 



lowing observations were 

 being made, was placed 

 at 10 beneath the horizon, 

 and it rose only 59 in 

 24 h. It behaved rather 

 differently from any other 

 plant, observed by us, for 

 during the first 4? h. it 

 rose in a line not far from 

 straight ; during the next 

 6 h. it circumnutated, 

 that is, it descended and 

 again ascended in a 

 strongly marked zigzag 

 course; it then resumed 

 its upward movement in 

 a moderately straight line, 

 and, with time allowed, 

 no doubt would have be- 

 come upright. In this 

 case, after the first 4 h., 

 ordinary circumnutation 

 almost completely con- 

 quered for a time apogeo- 

 tropism. 



Brassica oleracea. The 

 hypocotyls of several 

 young seedlings placed 

 horizontally, rose up ver- 

 tically in the course of 6 

 or 7 h. in nearly straight 

 lines. A seedling which 

 had grown in darkness to 

 a height of 2i inches, and 

 was therefore rather old 

 and not highly sensitive, 

 was placed so that the 



ronffe: ipogeotropic move- hypocotyl projected at be- 

 ment of cotyledon, traced on a vertical tween 30 and 40 beneath 

 and horizontal glass, from 9. 10 A.M. Sept. tne horizon. The upper 

 19th to 9 A.M. 20th. Figure here re- 

 duced to one-fifth of original scale. P^ alone ^came CUrVed 



