CH. Vn] KLINOSTAT. 175 



and (ii), but the plant is arranged so that its axis is at 

 right angles to the spindle. The leaves behave in the 

 same way as if the plant was stationary, that is to say, 

 those pointing towards the light curve downwards, while 

 those pointing away from the light move upwards until 

 the laminas of both are at right angles to incident light*. 



(217 a) Exclusion of hoik heliotropic and geotropic 

 curvature. 



If the klinostat is arranged so that the spindle is 

 parallel to the plane of the window, heliotropic as well as 

 geotropic effects are avoided. This may be simply shown 

 by keeping a pot of young mustard seedUngs rotating for 

 a day or two, and observing that they do not curve 

 but remaiQ straight. 



(218) Rectipetality. 



A pot of young mustard seedlings which have been 

 grown in the dark is placed on the klinostat with the 

 axis of the plants parallel to the spindle. The clock is 

 stopped and the plants allowed to remain in one position 

 in the dark, until, a measurable geotropic curvature 

 is produced. The clock is then set in motion and after 

 24 to 36 hours the curvature is found to be greatly 

 diminished or to have quite disappeared. This automatic 

 recovery from growth curvature has been named recti- 

 petaUty by Vbchting". 



' Into the difficult question of the behaviour of the lateral leaves on 

 the kUnostat we do not propose to enter. 



^ Die Bewegungen der Bliithen und Friichte, 1882. 



