The Philippine Journal op Science, C. Botany. 
Vol. XI, No. 5, September, 1916. 
GROWTH PHENOMENA OF DIOSCOREA 
By Edwin Bingham Copeland 
(From the College of Agriculture, University of the Philippines, Los 
Banos, P. I.) 
Studies of Dioscorea of several kinds have been in progress at 
the College of Agriculture during the past three years. These 
studies, before this year, have included the systematic determi- 
nations (by Mr. I. H. Burkill), the preparation of keys for the 
identification of varieties, the investigation of behavior in the 
field of a large number of forms, studies of their chemical and 
culinary characteristics, and growth studies. Considerable in- 
formation as to the growth of different varieties, with notes 
as to growth movements, was collected by Mr. Mariano Ray- 
mundo in the preparation of a thesis, publication of which is 
delayed until Mr. Raymundo’s return from America. 
As a feature of the irregular postal service during these years 
of war, reviews of the Pfeffer Festschrift 1 reached Manila in 
advance of the Festschrift itself. From one of these reviews I 
learned of Professor Newcombe’s work, “Das Verhalten der 
Windepflanzen in der Dunkelheit,” 2 and was immediately struck 
by the natural advantages with which Dioscorea would lend itself 
to such study. It presently developed that Duchartre 3 had long 
since used Dioscorea batatas for this purpose and that De Vries 4 
repeated Duchartre’s experiments, both agreeing that there was 
neither circumnutation nor twisting except under the immediate 
or deferred influence of light. 
As neither of these papers, nor any other available literature 
in the same field, showed any reason for a relation between nuta- 
tion and illumination, and as a supply of roots of various varieties 
of Dioscorea was on hand at the moment, I had a series of these 
roots placed where they might germinate. For this initial work, 
1 Jahrbiich. f. Wissenschaf. Bot. 56: (1915). 
2 Ibid., p. 511. 
3 Experiences relatives a l’influence de la lumiere sur l’enroulement des 
tiges. Comp. Rend. Acad. Sc. Paris 61 (1865) 1142. 
* Zur Mechanik der Bewegungen von Schlingpflanzen. Arbeit. Bot. Inst. 
Wurzburg 1 (1873) 327. 
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