78 THE PALM-STEM : 



torn away, in a circular direction in the greatest part of 

 its circumference. The isthmus is developed into the 

 petiole, the upper part of the vesicle becomes erected, 

 acquires the shape of a spoon, and is converted into the 

 leaf, the vagina of the leaf appears to grow out from the 

 wound which the torn leaf leaves upon the phyllophore. 

 The leaf acquires the form of a hood, its border having 

 an irregular thickening ; the two lateral halves of the hood 

 are formed of the two series of leaflets, and the thickened 

 edge, which unites the points of the leaflets, subsequently 

 becomes absorbed. 



The description of this process does not agree in the 

 least with what I observed in regard to the earliest period 

 of the formation of the Palm leaf. I examined, in reference 

 to these statements of Mirbel, the terminal buds of 

 Phoenix and Cocos flexuosa^ but found, as in other Mono- 

 cotyledons, such as ^ave, Yucca, no trace of origin of 

 the leaf under the form of a circularly torn vesicle as de- 

 scribed by Mirbel, but saw the leaves shoot forth from 

 the axis in the form of obtuse papillae. This papilla is at 

 first narrow, in proportion to the portion of the axis on 

 which it stands, since the first-formed part of it corre- 

 sponds to the apex of the future leaf; the further it is 

 developed, the more the base rises from the surface of the 

 stein, so that in the Palms an indication of the vagina of 

 the leaf is visible at a very early period. I cannot under- 

 stand how Mirbel came to the idea that the leaf originates 

 in the form of a vesicle, and that several such vesicles lie 

 one above another ; he must have been led to this view by 

 a longitudinal section which did not pass exactly through 

 the axis of the bud, and thus have met with sheaths of 

 young leaflets (which in the inner parts of the bud are not 

 cylindrical, but have the lower part spread out almost flat), 

 and have taken them for the rudiments of the whole leaves. 

 I deduce another reason against the assumption that the 

 leaflets originate from closed vesicles, from the observation 

 of a monstrous formation which I found in a branch of 

 Phcenix, the axis of which had grown out to the length 



