288 ME. D. T. GWYNNE-VAUGHAN Oi^ THE 



exaggeration of the peltation of such a bowl-shaped peltate lamina as that of Nelumbiunit 

 the operculum representing a portion of the lamina unaffected by the peltation, this 

 hood or terminal lobe of the young Euryale leaf might well be compared with the 

 operculum of a pitcher. The great similarity between the early development of the 

 pitchers and of peltate leaves, such as those of Victoria and NeluniUnm^ also tends 

 to show that a comparison between the two is not altogether fanciful. 



The methods of origin of a piicher on the one hand, and of a peltate lamina on the 

 other, as respectively described by Bovver* aad Treculf are fundamentally identical. 

 The first indication of each is the appearance of a shallow depression on the adaxial side 

 of the leaf -rudiment, just below its apex ; which depression is caused by the slow growth 

 of a central area relative to that of the regions surrounding it. A single point of 

 difference is that in Nelumhium the growth of the region at the base across the summit 

 of the petiole is for a time delayed, so that, to begin with, the central depression is but 

 incompletely surrounded by a horseshoe-shaped emergence instead of a complete annular 

 cushion. However, the delayed region soon takes up a more rapid growth, joining the 

 two arms of the horseshoe transversely across the summit of the petiole ; then the whole 

 grows out into the peltate lamina. 



Prof. Bower has shown (/. c.) that the operculum of the pitcher is at first a two-lobed 

 structure, which he regards as representing two pinnae congenitally coalescent across the 

 adaxial surface of the leaf. It is known that in certain peltate leaves, as in ILydrocotyle 

 vulgaris % and in Tropceolum majus (Trecul, I. c), the earlier stages are seen to be very 

 distinctly lobed with a terminal unpaired lobe. With this fact in view, it becomes easy to 

 suppose that in the pitchers, themselves originating in a lobed leaf-rudiment, the upper 

 pair of lobes may remain free from the peltation of the rest of the leaf, to form an 

 operculum in the manner described by Prof. Bower, while the terminal lobe grows out 

 into the spur found at the point of the insertion of the operculum on to the pitcher on 

 the dorsal side. 



The prickles and spines which beset the under surface of the adult leaves of Victoria 

 re(jla are also clearly visible on young leaves which have attained a length of about 

 5 mm. Before that size is reached, although the petiole and the lamina with its principal 

 veins are already clearly developed, the prickles are not yet visible. They first make 

 their appearance as little rounded projections on or near che midrib, at the points where 

 the lateral veins join on to it, the midrib being at this stage by far the principal vein in 

 the leaf. Most of the larger prickles are traversed by a narrow strand of vascular tissue, 

 and they are said by Trecul § to terminate in a " pore " or " ostiole " which opens below 

 into a small cavity. My observations, however, entirely confirm those of Mr. Blake 

 (Ann. Bot., i. p. 71), who failed to find any trace of this pore. I noticed, however, that 

 if the tip of one of these prickles be viewed directly from above, the rounded terminations 

 of a number of cells which are arranged in a ring around a central one give an aj)pearance 



* Ann. of Bot., vol. iii. p. 239. t Ann. des Sc. Nat., at-r. 3, vol. xx. p. 2GL 



t Goebel, Schenk's ' Handbuch dcr Bot.,' Band iii. late Hiilfte, p. 234. 

 § Ann. des Sc. Nat,, ser. 4, torn. i. p. 156. 



