248 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



prolonged midrib to the point of articulation with the lid. This 

 operculum or lid is a remarkable organ which, after being opened, 

 stands high above the aperture in a horizontal or ascending 

 direction, being raised by the triangular process on which it is 

 articulated. Around the aperture is the peristomium, a ring 

 which varies much in the different species in breadth, colour, 

 and shape ; the inner edge of this ring is armed with sharp teeth 

 which effectively prevent the escape of the entrapped insects. 

 The peristomium is a striking ornament of the pitcher in the 

 curiously shaped pitcher of Lowii the peristomium is absent, the 

 only known case. In all the species there is a sharp spine on 

 the dorsal side at the articulation of the lid and pitcher ; in 

 bicalcarata, in addition to this there are two strong sharp spurs 

 on the opposite or inner side, whence the specific name. The 

 pitcher in its perfect form, as I have attempted to describe it, 

 takes an erect position with the ventral side opposite and often 

 pressed against the prolonged midrib of the blade. The change 

 in shape and size now about to be pointed out takes place much 

 in the same manner in every species and hybrid, so that when 

 this change has reached an advanced stage it is difficult to 

 identify from the pitcher itself to what species it belongs. 

 These changes in size and form are also accompanied by a 

 change in colour. 



As leaf after leaf is produced from the ascending stem, the 

 pitchers first become longer and narrower; then follows a 

 gradual diminution of the parts while the pitchers are being- 

 modified from the flask-like to the cylindric shape ; the ventral 

 wings constantly diminish in breadth and the ciliate fringe dis- 

 appears until the place of the wings is denoted only by two 

 narrow keels, and instances have been observed in which even 

 these are obliterated. The pitchers not only undergo change in 

 size, form, and colour, but they also change their position in 

 respect to the prolonged midrib. By the time the seventh or 

 eighth pitcher has been produced above that which we have 

 already referred to as the perfect pitcher, the prolonged midrib 

 has made half a revolution on its own axis, so that the pitcher has 

 now its dorsal side towards it. As the pitchers diminish in size 

 with the ascent of the stem, so when a certain stage of growth 

 is reached, and as the plants arrive at the time of flowering, they 

 cease to be produced altogether, but the stem continues to grow 



