Fig. 36: 



ORfiANS OF XUTRITIOX. 



Fig. 368. 



183 



Fig. 369. 



Fig. 3C7. Pitcher of a species of Pitcher plant (Xepenthes distiHatoria). p. 



Pitcher closed above by a lid, 1 Fig. 368. Pitcher of a Side-saddle plant 



iSarracenia purpurea). Fig. 369. Pitchers of Ileliamphor a. 



by a lid called an operculum, united to it by an articulation. The 

 lid is here regarded as a remarkable transformation of the blade. 

 This kind of pitcher is looked upon by some botanists as a modi- 

 fication of such leaves as the Orange (Jig. 300), and Venus's 

 Fly-trap (Jig. 352), in which the petiole is articulated to the 

 blade ; thus, if we suppose the winged petiole of such plants to 

 fold inwards and unite by its margins a pitcher would be formed 

 resembling that of Xepenthes, and the jointed blade would then 

 be seen to be clearly analogous to the operculum or lid of that 

 plant. According to Griffith, the pitcher of Nepenthes is a 

 modification of the excurrent midrib or the stalk of the pitcher, 

 and Dr. Hooker has recently confimied his obseiwations, and 

 shown that it is formed out of a gland situated at the apex of the 

 midrib. In the Dischidia, the pitchers are considered to be formed 

 by the folding inwards and union of the margins of the lamince 

 or blades. Other botanists consider the pitchers of Xepenthes 

 and Sarracenia as petioles hollowed out towards their extremi- 

 ties, but the opinions given above as to their origin appear far 

 more likely, and conformable to observation in other cases, 



8. GENERAL VIEW OF THE LEAVES IN THE THREE GREAT 

 CLASSES OF PLANTS. 



We have already seen in describing the structure and general 

 characters of the stems and roots, that they present well marked 

 distinctive characters in the three great classes of plants. We 

 N 4 



