OF THE PITCHERS OF NEPENTHES. 417 



dltiou; for in some very young leaves of iV^. BoJJlesiana 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 (iig. 11), thus forming a convolute 

 vernation ; l)ut 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 cylindi-ical 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 coHvolute condition of these organs. 



In the above description I have used tlie term adopted by GrifRth, of " cxcurrent 

 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, &c. ; and thougli 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 mouocotyledonous and dicotyledonous plants. In young Limnocharis Plmuieri, 

 especially, a gland is placed at the apex of the midi'ib, and being hollow, resembles the 

 early condition of the Neijenthes 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 Avhole 

 subject. One of these (species unknown) is figured of the natural size in Tab. 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 tliat of Sarra- 

 cenia. The youngest leaves I have examined, namely those immediately succeeding the 

 cotyledonary, have a more or less dilated lamina, and a hollowed-out upper half of the 

 midrib, partially closed with a small ciliated lid ; as the leaf grows, the lamina dilates 

 upwards on each side, so as to become cuneate, and finally obcordate and bilobed at the 

 apex, with the pitcher in the sinus. "When fully developed, these leaves are about ^-f inch 

 long ; they present on the upper surface a shallow mesial groove, leading up to a triangular, 

 slightly tumid area towards the apex, which area answers to the anterior face of the pitcher ; 

 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. 



Looking at the under surface of the leaf, the midi'ib appears very stout below, and gi'a- 

 dually bulges as it advances towards the apex of the leaf, forming the belly of the pitcher. 



* I have not yet sntisficd myself as to tlie origin of the pitcher in Cephalotio and Sarraceniacetf. 

 VOL. XXII. 3 I 



