112 Bulletin Jard. Bot. Buitenzorg, Série III, Vol. V. Livr. 2. 



verbunden mit nachheriger Spaltenbildung, an der Spreite die in Fig. 18 

 angedeutete Faltung erkennen lassen.'' 



With référence to the ultimate séparation of the leaflets, Nauaiann 

 says that it does not always occur, as ElCHLER maintains, through a dis- 

 organization process beginning at the periphery and working inwards, but 

 may resuit from the séparation or growing apart of ceils between segments. 



Deinega (^) does not add anything new to the conception of palm 

 leaf development. The part devoted to the palm leaf is a substantiation 

 of Goebel's point of view and a polemic against Naumann. The inade- 

 quacy of the figures does not lend force to any of his contentions. The 

 crucial point in the GOEBEL interprétation, namely the development of the 

 secondary enveloping tissue around the folds after folding has occurred 

 is discussed but no convincing proof is given. Deinega certainly did 

 not hâve enough material available to study ail the stages. 



it had not occurred to me that the material at my disposai v^ould 

 offer anything essentially new other than the formai description of leaf 

 development in a palm which has pinnate leaves. As the work progressed, 

 however, it became apparent that the last u'ord had not been said on leaf 

 development and that Elaeis giiincensis did not fall in line with either one 

 of the interprétations that of VON MOHL and Naumann who attribute 

 the partial or complète séparation of the parts of the leaf blade to splitting 

 of the originally intact blade surface, nor did it fall in line with the inter- 

 prétation of Goebel, namely, that the leaf blade folds due to the limited 

 space it has for development and séparation occurs through disintegration 

 of tissue between the folds. 



Material and Methods. 



The work was begun in Medan, Sumatra, at the „Algemeen Proef- 

 station der A. V. R. O. S." where ail stages for investigation were available. 

 Not only were the plants growing there used but the oil palm plantations 

 on the East Coast of Sumatra also served as sources of supply for ma- 

 terials needed. Later the work was transferred to Buitenzorg, Java, where 

 additional material was available. The investigations on the leaf were made 

 with seedlings in ail stages and with trees up to five years of âge. Obser- 

 vations were made both on living and fixed material. For studying the 

 living material a Zeiss binocular was employed. For fixing material Juels 

 solution was used and staining was done with iron-haematoxylin. 



General discussion of leaf. 



As in ail palms the first leaves of the young plant are undivided. 

 The transition from the undivided first leaves to the fully mature divided 

 leaf is a graduai one. The first leaves (5 to 7 as a rule) are lanceolate 

 with fairly strongly developed ribs Due to the strcngly developed sheath 



