MEMOIRS OF THE NEW YORK BOTANICAL GARDEN. 309 



light was supplemented by nocturnal illumination from electric arcs, or 

 flames. In all such instances the amount of growth, as indicated by 

 the length of the shoots and of the separate members, was greater 

 than under ordinary conditions of alternating dayhght and darkness. 

 If light exerted a direct retarding, or paratonic influence upon the 

 processes of growth, such results would be impossible. On the 

 other hand, if the slowing down of the increase of shoots when sud- 

 denly exposed to light is due to a stimulative action the continued il- 

 lumination of a plant to the action of the rays would soon result in an 

 accommodation to the continuance of the stimulation, and the be- 

 havior of the plant after becoming attuned to increased illumination 

 would embrace some features due to the altered conditions of nutri- 

 tion, and to the supposedly disintegrating effects of the blue-violet 

 rays on chlorophyl and other substances. 



