174 KLINOSTAT. [CH. VII 



The following fundamental experiments should be 

 performed^ 



(i) When a Ficaria plant is dug up, its leaves freed 

 from the resistance of the soil, curve (epinastically) strongly 

 downwards. If the plant is fixed with its axis horizontal 

 and parallel to the spindle of the klinostat, and if the 

 klinostat is placed with the spindle at right angles to the 

 plane of the window, the leaves will be pointing almost 

 directly away from the light. The angular divergence 

 from the vertical of a few leaves having been noted the 

 klinostat is set in movement. After two or three days it 

 will be found that the leaves have curved towards the 

 light, and that they have come to rest in such a position 

 that the laminas are about vertical, i.e. at right angles to 

 the horizontal illumination from the window". 



(ii) Dig up a Ficaria with a large ball of earth (so 

 that the epuiastic curve cannot occur), and place it in the 

 dark, in which case the leaves will bend upwards. Leave 

 it ih the dark until the leaves are about 45° above the 

 horizon, and fix it on the klinostat precisely as described 

 for (i). The leaves will now be pointing more or less 

 towards the light, and in two or three days they will have 

 curved away from the light until their laminas are ap- 

 proximately vertical. 



(iii) In this experiment the klinostat stands as in (i) 



^ See F. Darwin, loc. cit. ; also Voohting, Bot. Zeitung, 1888 ; &abbe, 

 Frinysheim's Jahrbueher, Vol. xx. ; Schwendener and Krabbe, K. Preuis. 

 Akad. Abhand. 1892. 



" Strictly speaking it is the resultant of the illumination which gives 

 the effect of horizontal light. See P. Darwin, loc. cit. p. 427. 



