Chap. X 



APOGEOTEOPISM. 



49r> 



horizontally, and the upper part of the stem rose 58° in 46 li.; 

 in the manner shown in the accom- 

 panying diagram (Fig. 185). "We here ^'S- '^5. 

 see that during the whole of the 

 second day of 15 i h., tlie stem plainly 

 circumnutated whilst bending upwards 

 tlu-ough apogeotropism. It had still 

 to rise considerably, for when the last 

 dot in the iigure was made, it stood 

 32° from an iipright position. 



PhalaiHs Caiiarienxis. — A cotyledon 

 of this plant (1"3 inch in height) has 

 already been described as rising in 

 4 h. 30 m. from 40° beneath the hori- 

 zon into a vertical position, passing 

 through an angle of 130° in a nearly 

 straight line, and then abruptly be- 

 ginning to circumnutate. Another 

 somewhat old cotyledon of the same 

 height (but from which a true leaf 

 had not yet protruded), was similarly 

 placed at 40° beneath the horizon. For 

 the first 4 h. it rose in a nearly straight 

 course (Fig. 186), so that by 1.10 p.m. 

 it was highly inclined, and now apo- 

 geotropism acted on it with much less 

 power than before, and it began to 

 zigzag. At 4.15 P.M. (i.e. in 7 h. from 

 the commencement) it stood vertically, 

 and afterwards continued to circum- 

 nutate in the usual manner about the 

 same spot. Here then we have a 

 graduated change from a straight up- 

 ward apogeotropic course into circum- Zilium auratum : apogto- 

 nutation, instead of an abrupt change, t^'op'" movement of stem, 

 as in the former case. 



Avena saiiva. — The sheath-like coty- 

 ledons, whilst young, are strongly apo- 

 geotropic ; and some which were placed 

 at 45° beneath the horizon rose 90° in 

 7 or 8 h. in lines almost absolutely 

 straight. An oldish cotyledon, from which the first leaf began to 



traced on a vertical glabs 

 during 2 days and 2 

 nights, from 10.40 A.M. 

 March ISth to 8 A.M. 

 20th. Figure reduced to 

 one-half of the original 

 scale. 



