THE PHYSIOLOGY OF PITCHER-PLANTS. 98 



occur in eleven genera (including Lathrsea) of Phanerogams 

 belonging to six more or less widely separated dicotyledonous 

 Natural Orders. With regard to their respective habitats, these 

 plants are mostly either aquatic and floating (many species of 

 Utricularia), or such as grow in more or less damp soil ; Dis- 

 chidia, however, is an epiphyte growing on trees, and therefore 

 in a dry situation ; whilst Latlmea grows in woods, being- 

 parasitic on the roots of trees. 



I will only say, with regard to the general morphology of the 

 pitchers, that each pitcher is either an entire specially modified 

 leaf, or less commonly {e.g. Nepenthes, often in Utricularia) a 

 specially modified part of a leaf. They vary widely in size, being 

 often several inches, or even two feet or more long in the Sarra- 

 ceniace^, whilst in Utricularia they are minute and delicate in 

 structure. This difference in size and consistence is recognised 

 in the technical terms which have been applied to these struc- 

 tures. Thus, Linmeus ("Aruoen. Acad.," vol. 6, p. 232, 1763; 

 also, " Philosoph. Bot.," Rose's Engl. Edn., p. 247, 1775) di 

 tinguishes the bladders of Utricularia as folliculi, from the 

 pitchers of Nepenthes and Sarracenia which he terms utriculi ; 

 similarly, Willdenow (" Principles of Botany," Engl. Edn., p. 80, 

 1811) designates the pitcher by the still accepted term ascidmm, 

 and the bladder by the term ampulla. 



A point of special interest is the fact that in some genera 

 (Sarraceniaceae, Nepenthes, Cephalotus) the pitchers are closed 

 during the early stages of their development. The opening is 

 effected in the SarraceniaceaB by a splitting of the tissue in the 

 middle line of the ventral surface of the pitcher near its apex, so 

 that a narrow aperture, with a well-developed margin, is formed, 

 which enlarges with the subsequent growth of the pitcher. In 

 pitchers with this mode of dehiscence the^apical portion beyond 

 the aperture is often considerably developed into a broad 

 flattened (as in Sarracenia) or inflated " hood " (as in Darling- 

 tonia). In Nepenthes and Cephalotus, on the contrary, the 

 dehiscence of the pitcher closely resembles the circumscissile 

 dehiscence of such fruits as those of the Pimpernel and the 

 Henbane, so that a lid or operculum is distinctly marked 

 off, remaining attached to the rim of the pitcher by a narrow 

 articulation. In describing these various pitchers the term 

 " operculate" has been used indiscriminately, whereas it is clear 



