178 Professor JDickson on the 



as a small depression or fossa a little to the inner side of 

 the extremity of the cone which represents the young leaf. 

 This fossa — the result of inequality of development in the 

 different portions of the extremity of a leaf whose petiolar 

 and vaginal portions already exist — he holds to be formed 

 on the upper surface of the lamina. The fully-developed 

 pitcher he views as corresponding morphologically to a 

 peltate leaf like that of Nelumbium. The large but shallow 

 inverted cone which forms the leaf-blade in Nelumbium 

 becomes in Sarracenia deeper and narrower, so as ultimately 

 to present the form of a long obconical horn. The pitcher- 

 lid he considers as merely the terminal lobe of tlie peltate 

 limb. 



If Baillon is right — as probably he is — in viewing the 

 pitcher of Sarracenia as a modification of a peltate leaf, it 

 would, in this respect, seem to differ considerably from that 

 of Geplialotus. In Sarracenia the whole outer surface of 

 the pitcher, on the near as well as on the far side from the 

 main axis, would represent lower leaf-surface ; whereas in 

 Geplialotus the upper surface of the pitcher-lid and the 

 portion of the outer surface of the pitcher-wall intervening 

 between it and the extremity of the petiole, and bounded 

 laterally by the " lateral lines " above referred to, belong to 

 upper leaf-surface. 



As regards Nepenthes, Hooker's observations conclusively 

 show that the pitcher-cavity is the result of a pouching 

 from the upper leaf-surface, and that the leaf-apex is 

 represented by the " styliform process" which projects from 

 behind the junction of the lid and pitcher. The lid here 

 must be viewed as an outgrowth or excrescence from the 

 upper leaf-surface, just as in Oq)halotus : with this 

 difference, however, that while in Ccphalotus the lid 

 springs from the side of the pitcher orifice nearest to the 

 main axis, the lid in Nepenthes springs from the side 

 farthest from it. 



The pitcher-leaf of Nepenthes presents, as is well known, 

 very considerable difficulties to the morphologist who wishes 

 to reduce its parts to the terms of " petiole" and " lamina." 

 The flatly expanded portion, sometimes sessile and some- 

 times supported by what closely resembles a petiole, is con- 

 sidered by Hooker as the lamina, whose midrib is produced 



