684 



LECTURE XXXIX. 



well as the shoot consisting of several internodes, is elongating; subsequently the 

 growth ceases at the base of the segmented stem, and only a certain portion of it 

 beneath the apical bud forms the growing region — the region capable of geotropic 

 curvature. In the case of individual internodes of sharply segmented shoot-axes, the 



FIG. ^85.— A klinostat. a the clockwork, with weight and penduUim, which slowly rotates the axis 

 b b: on this axis is fixed a cube of bread at c on which a Fungus (Pkycomyces) is growing. Tlie middle 

 portion of the axis is surrounded by a glass box d, which stands on a dish filled with water, in order to 

 keep the air around the plant moist (about -j-^ nat. size). 



subsequent growing region may be situated near either the apex or the base : apical 

 growth is the usual, basal growth the rarer case. 



The length of the growing region, if parts which are already fully developed are 

 present, is at a certain time at a maximum and then decreases, to fall to zero finally 

 when the whole stem is fully developed. In that middle period I found, in cases 

 where the growing region was very long, the lengths quoted on page 543. 



