338 BOTANICAL GAZETTE [april 



Ontogenetic evidence 



Hemerocallis fulva L. — An apical bud of this plant was dissected 

 on March i. Neither in a leaf about i mm. long viewed under the 

 simple microscope, nor in younger leaves examined with the com- 

 pound microscope, could any distinction be discerned between the 

 " leaf -sheath " and the rest of the leaf. The leaf is open to the 

 extreme base, so that no closed sheath is formed. 



S cilia hispanica Mill. — The young foliage leaves for the current 

 year were examined on March i. All the leaves, down to the 

 youngest, were found to be similar structures, in which the hooding 

 of the apex was a relatively more conspicuous feature than in the 

 older leaves. In the mature leaf, the sheath is seen to be closed 

 for a very short distance at the base. 



The conclusion to be drawn from the development of the leaves 

 of these two species seems to be that in the case of Hemerocallis 

 there is no evidence from the ontogeny of the existence in the leaf 

 of any region except the leaf -base or leaf-sheath; in S cilia the main 

 part of the leaf seems also to be of leaf-base nature, although the 

 apical region of the hooded tip may possibly bear another interpre- 

 tation, to which reference will be made later. 



Evidence of comparative morphology 



In order to test the interpretation here suggested, which explains 

 the leaves of Tulipa, etc., as essentially leaf-base members, a 

 search was made for some dicotyledon possessing both leaves with 

 a well differentiated leaf -base, petiole, and lamina, and also reduced 

 leaves which could be closely compared with those of the mono- 

 cotyledons in question. Such a plant was found in Fatsia japonica 

 Decne., of the Araliaceae, often cultivated under the name of 

 A r alia. The normal foliage leaves of this plant are shown in 

 fig. i A. There is a well marked sheathing leaf -base (b), a petiole 

 (p), and a palmate lamina. In addition, there are transitional leaf 

 forms with reduced blades, culminating in bladeless bud-scales 

 (fig. iB). These are of the same nature as the leaf-base of the 

 normal leaf, although they are thinner in texture, and the parallel 

 veining is more obvious. The most interesting feature, however, 

 is that the apical region of the bud-scale, which is developed in 



