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 x 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 * 

 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, 



'Jahrbucb. f. Wissenschaf. Bot. 56: (1915). 



2 Ibid., p. 511. 



'Experiences relatives a l'influence de la lumiere sur l'enroulement des 

 tiges. Comp. Rend. Acad. Sc. Paris 61 (1865) 1142. 



4 Zur Mechanik der Bewegungen von Schlingpflanzen. Arbeit. Bot. Inst. 

 Wiirzburg 1 (1873) 327. 



227 



