YAMPOLSKY: Stiidy of OU paliii. 120 



tlirough the sliifting of the plane of grovvtli. Wc liave seen in tlie oil palm 

 that thèse leaflets are separate units held together at their free ends by the 

 strip at the edge of the lamina and by the thiii, frayed and torn enveloping 

 layer. A mère mechanical tearing of the strip at unfolding libérâtes thèse 

 leaflets and inasmuch as the leaflets were for the most part always free no 

 disorganization of definite tissue between them functions in a manner 

 described by ElCHLER. Certainly ElCHLER's figures 11, 12, 13, 14 Plate I 

 are not very convincing for the argument advanced. The same criticism 

 holds for his figures in the other |)lates showing disorganization of tissues 

 in the act of liberating the segments and leaflets. ElCHLER's contribution 

 is a substantiation of HOFMElSTER's and GOEBEL's interprétations. 



Naumann's observations on a large number of forms deserve more 

 crédit than iiitherto lias been accorded them. His work is an amplification 

 of that of VON MOHL and he was able to contribute much to our knowledge 

 of the formation of the palm leaf. Naumann observed that before the ap- 

 pearance of the slits which VON MOHL dèscribes, swellings occur and that after 

 their appearance the slits become apparent. NAUMANN always associâtes 

 thèse two phenomena. He goes even further back, in his Figures 4' to 4^ 

 Plate IV, to show the origin of the swellings and slits and the epidermis 

 or "Haut". The figures are entirely unconvincing and misinterpreted by 

 him. Thus, for instance, his Figures 4^ and 4^ Plate IV, are not beginning 

 stages of the formation of swellings and slits but they are cross sections 

 of several fairly well developed leaflets which hâve grown obliquely upwards 

 and which lie closely pressed together. 



As we hâve already pointed ont the nature of the epidermis or "Haut" 

 is the critical point in testing out GOEBEL's theory of the origin of the 

 leaflets since he believes it to be a secondary development, arising after 

 folding of the lamina has taken place. NAUMANN recognizes that this is 

 the crucial point. He attempts to show the présence and development of 

 this epidermis before folding has occured and that it is a part of the leaf 

 and not an accessory structure as GOEBEL maintains. His observation are 

 only in part correct since we hâve seen that the epidermis or "Haut" 

 existed before there was any indication of leaflet development. 



The attempt of Naumann to trace back the origin of the swellings 

 and the slits to definitely localized régions within the growing leaf, although 

 erroneously figured, was an attempt that would hâve yielded more fruitful 

 results had the right technique been available. 



To VON MOHL and to NAUMANN must be given their due crédit in 

 the interprétation of the phenomena of leaflet and segment origin in the 

 palms. Both of thèse authors did not go back far enough in the young 

 stages to see what is actually going on within the deliminated lamina. 



The steps in the formation of the leaf m {\\Q0\\\)2i\m {Elaeis guineensis 

 JACQ.) used as a basis for contrast with what has been described in other 

 palms, calls for a reinvestigation of the origin of the leaf in the Palmae. 



