2 26 MEMOIRS OF THE NEW YORK BOTANICAL GARDEN, 



tiveness is increased liowever, and etiolated plants show some diver- 

 gence from the normal in reaction time and amount of increase in 

 intensity necessary to constitute a stimulus. ^^'' 



All of the climbing species examined in the dark room at the New 

 York Botanical Garden were apogeotropic, and the stems assumed 

 an erect position, falling over from their own weight as soon as a 

 certain height had been reached. The development of Meni- 

 spermum was accompanied b}' but slight manifestations of this char- 

 acter however, and the comparatively short stems remained in an 

 upright position in most instances. It is most notable that none of 

 the five species examined by the author, Apfos, Aristoloc/ifa, Bozc/ea, 

 Judicata and Meiiispcrninni, in which adequate stems were devel- 

 oped, were capable of twining around a support, although repeated 

 tests of this particular phase of the reaction were made. Moreover 

 the nulatory movements of the apices of the etiolated stems were of 

 much narrower amplitude than in the normal. 



Duchartre recorded that Dioscorea Batatas and Manda suave- 

 olens did not exhibit twining in darkness when fully etiolated, but 

 that when normal plants were brought into a dark room twining con- 

 tinued for some time, the apical portion of the stem finally assuming 

 an upright attitude."" These results w^ere confirmed by de Vries.'®* 

 Sachs' experiments appear to offer evidence to the contrary, since 

 he found that etiolated internodes of Tpomaca purpurea and Phascolus 

 muItiflorHS were capable of attachment to a support by twining around 

 it. An examination of his technique shows that such results were 

 obtained in " partial " etiolations onl}-, in which the apical por- 

 tions of stems were thrust into small chambers through openings 

 sealed with cotton, wool or other fiber, thus introducing the vitiating 

 action of possible imperfect exclusion of darkness and the positive 

 stimulative influence of light on the free portion of the stem.""^ 



'®- Figdor, W. Versuche ueber die heliotropische Empfindlichkeit der Pflanzen. 

 Aus. d. Sitzungsber. d. kaiserl. Akad. d. Wiss. i. Wien, 102 : Abth. I. 1893. See 

 references given in above paper to Wiesner's researches. 



'*^ Duchartre. Compt. Rend. 61: 1142. 1865. 



'^'De Vries. Zur Meciianik der Bewegungen von Schlingpflanzen. Arb. a. d. Bot. 

 Inst. i. Wurzburg, 3 : 317. 1873. 



'^' Sachs. Wirkung des Lichts auf die Bliithenbiidung unter Vermittlung der 

 Laubbiiitter. Bot. Zeitung, 23 : 117. 1865. 



