432 



ME. F. E-AEWIN ON THE POSITION OP 



It will be seen that, instead of diminishing, the epinastie curva- 

 ture increased in all three cases. The tin box was then removed 

 from the klinostat, and placed so that the plant was in the normal 

 position ; in a few days leaves i. and ii. (iii. was not noted) were 

 well above the horizon, showing that their behaviour during the 

 rotating was not due to cessation of growth. 



It has now been proved that the antagonism of apogeotropism 

 and apheliotropism is not necessary to the plant. But it may be 

 said that, as the leaves are undoubtedly strongly epinastie, the 

 balance may be due to the equality of epinasty on one side, and 

 apogeotropism aided by positive heliotropism on the other. The 

 following experiment disproves this view. 



Experiment 4. — A plant was dug up on April 29th, 9.27 A.M., 

 with a large ball of earth attached, so that the leaves were unable 

 to bend backwards. The plant was placed in the dark until 

 the leaves had become somewhat raised above the horizon ; it 

 was then placed on the klinostat in the zenith position, so that 

 the leaves were pointing towards the light (April 29th). 







Table IV. 







Date. 



Leaf i. 



Leaf ii. Leaf iii. 



Leaf iv. 



i April 29, 1 

 9.27 a.m.] 



'April 30,1 

 8.30 a.m. ; 



May 30, 1 

 3.30 p.m.] 



Lamina 

 +90 chd* 



+45 



+25 



Lamina 



O 



+24 

 -23 

 — 5 



Lamina 



o 

 +45 



+20 



+ 5 



Lamina 

 o 

 +45 



- 1 

 J twisted 

 \ sideways. 



This (though not a very complete experiment) shows clearly 

 enough that the leaves are not heliotropic, since they all at first 

 curve away from the light ; by glancing down any one of the 

 columns headed " Lamina," it will be seen that all the angles be- 

 come smaller, and in some cases the sign changes. In other 



executed when the plant was on the klinostat, showing the existence of power 

 of curving forward. It need hardly be said that I took care not to be deceived 

 by the sleep-movements in estimating the movements with regard to the direc- 

 tion of incident light. 



* chd means that the organ measured was so much curved that it was only 

 possible to measure the angle made by the chord of its arc with the transverse 

 plane. 



