LEAVES WITH EEGABD TO LIGHT. 437 



On April 2nd, the leaves being 45° and 35° behind the trans- 

 verse plane, the plant was fixed on the klinostat in the nadir 

 position (p. 427). On April 5th the leaves had curled round in 

 consequence of continuous epinasty, so that the upper surfaces 

 were, as shown in fig. 9, partly illuminated. "What was the mean- 

 ing of the subsequent movement which occurred on April 7th I 

 cannot say ; but as it occurred on both leaves, it is perhaps worth 

 giving : the consequence was that the leaves pointed towards the 



light. 



Fig. 9. 



t t 



Diagram illustrating the position of the leaves on April 5th, Table IX. The 

 arrows show the direction of the incident light. ^^ ^' 



Experiments with Beans (Vicia Faba). 



A very young plant was transplanted (May 17th) from the open 

 ground and kept under a bell-glass in the greenhouse for a couple 

 of days, during which time it was subjected to a rather dull light 

 from above. On May 19th (10.30 a.m.) two of the leaves were 38° 

 and 41° above the horizon, and the plant was placed on the klino- 

 stat in the zenith position. On May 21st, 8.26 a.m., one leaf was 

 + 16°, the other —2°. The experiment having been made to 

 observe the " sleep " movement of the bean on the klinostat, was 

 not continued any longer. There was evidence of power of bendiug 

 in front of the transverse plane independently of apogeotropism; 

 that is to say, the plants performed their sleep movements while 

 on the klinostat. 



The same experiment was repeated in the autumn. On Oct. 

 27th, 9.20 a.m., a plant 15 centim. high was removed from a 

 shady part of a cool greenhouse and fixed on the klinostat m the 

 zenith position. The two leaves next below the bud were ^chosen 

 for observation^, (the younger leaf) being at +62°, ii. at + 15°. On 

 Oct. 29th, 9.20 a.m., leaf ii. was -15°, on the same day in the evening 

 (0.50 p.m.) at +12°, the change being due to "sleep movement," 



2k2 



