OF THE PITCHERS OF NEPENTHES. 417 
dition; for in some very young leaves of N. Rafflesiana I observed, that as the frontal 
groove which represents the anterior (or upper) surface of the leaf deepened and its 
margins expanded, these margins decidedly overlapped (fig. 11), thus forming a convolute 
vernation ; but that, owing to a more rapid growth of the overlapping hemiphyll, which 
still retained its initial tendency to curve inwards towards the midrib, it eventually 
formed a Cylindrical roll parallel to, and in contiguity with, the originally overlapped 
hemiphyll. 
If these observations should receive confirmation, they will tend to prove that the 
involute vernation of leaves may be, in some cases at any rate, a modification of the more 
frequent convolute condition of these organs. | 
In the above description I have used the term adopted by Griffith, of * excurrent 
midrib ;” but I need hardly say that the intermediate organ, or stalk of the pitcher, is no 
more an excurrent portion of the lamina, than is the petiole in those species where that 
organ is developed: it is a body more or less strictly analogous to the terminal cirrhus 
of the leaf of Gloriosa, Flagellaria, various species of Convallaria, &e.; and though the 
development of a gland at its apex into a pitcher is very anomalous, and possibly unique*, 
the existence of terminal glands in the leaves of plants, which is physiologically the most 
important feature, is by no means so unusual a fact as may at first sight appear. ‘They 
are very conspicuous at the apex of the leaf of Limnocharis, Caladium, and other genera, 
both of monocotyledonous and dicotyledonous plants. In young Limnocharis Plumieri, 
especially, a gland is placed at the apex of the midrib, and being hollow, resembles the 
early condition of the Nepenthes pitcher. 
Since the above observations were made, I have had the opportunity of examining some 
seedling Nepenthes, for which I am indebted to Hugh Low, Esq., of the Nursery, Clapton, 
and which are both extremely singular in themselves, and throw much light on the whole 
subject. One of these (species unknown) is figured of the natural size in Tax. LXXIV. 
fig. 19, and magnified at fig. 20. The first pair of leaves (fig. 20 a & 21), the cotyledonary, 
are opposite, lanceolate and acute; the following at once bear ascidia at their apices, of a 
size, form, and in a position that cause the whole leaf strikingly to resemble that Z 
cenia. The youngest leaves I have examined, namely those immediately me a; 
cotyledonary, have a more or less dilated lamina, and a hollowed-out —— dp 
midrib, partially closed with a small ciliated lid; as the leaf grows, 2 c = 
upwards on each side, so as to become cuneate, and finally obobidete A Kost La inch 
apex, with the pitcher in the sinus. When fully developed, these — € u F if Pa siå 
long ; they present on the upper surface a shallow mesial groove, Er re — ; 
slightly tumid area towards the apex, which area answers to the anterior face p ; 
beyond the apex the neck of the pitcher protrudes, with its lid; the margins of the leaf are 
carried up as wings along the sides of the neck of the pitcher to near its orifice, where they 
meet, and form a transverse, reflexed, ciliate membrane. 
Lookine at the under surface of the leaf, the midrib appears very år = je m 
dually Baines as it advances towards the apex of the leaf, forming the belly o p 
s to the origin of the pitcher in Cephalotus and nm 
31 
* I have not yet satisfied myself a 
VOL. XXII. 
