68 



L. LENORE CONOVER 



The tip of the main axis of a growing shoot undergoes num- 

 erous deflections from the vertical position, the most notice- 

 able of which are due to the lateral access of light during the 

 day, the overhanging older shoots cutting off a large part of 

 the light from above. This lateral ciu-ving during the day dis- 

 appears at night, when the negative geotropism of the shoot 

 takes it again to the vertical position. When the shoot has 

 nearly attained its definitive growth, having taken the trans- 

 verse position, and the lateral branches being well extended, 

 the tips of main axis and of branches nutate up and down, and . 

 present in this process the appearance of alternate wilting and 

 recovery. 



After successively longer and longer, non-twining shoots have 

 been sent up from the rhizome for a year, the twining shoots 

 appear, making a very narrow coil about the cord that may be 

 given them for support. They rise to great heights — 10 meters 

 or more. Experiments that were made failed to show any sen- 

 sitiveness to contact or pressure as an aid to climbing. 



I am greatly indebted to Prof. F. C. Newcombe for his valuable 

 suggestions and his kindness during my work in his laboratory, 

 where most of the material and apparatus for experimentation 

 were provided. 



