130 PLANTS WITH TRAPS AND PITFALLS TO ENSNARE ANIMALS. 



and Sarracenia variolaris cannot exercise this digestive action, for if it did the 

 maggots in the heap of rotting insects could not remain alive and well. Its 

 action is limited to the promotion of decay and the formation of a foul liquor, in 

 other words, a liquid manure, which is absorbed as nutriment by the epidermal cells 

 at the bottom of the pitchers. 



Another series of pitcher-plants comprises forms in which the petioles are 

 ■converted into symmetrical sacs with apertures at the top, and the lamina spread 

 •out over them like lids for protection. Most frequently the pitfalls in plants of 

 this kind are shaped like pitchers, jars, urns, cups, or funnels; and the lid over the 

 -orifice of each cavity is, for the most part, so placed as to prevent rain-drops from 

 falling in, but not to hinder in any way the entrance of animals. In this series are 

 included, firstly, a few species of Sarracenia, viz. Sarracenia Drummondii and 

 ■S. undtdata, next, the Australian Cephalotus follicularis, and lastly, the numerous 

 species of the genus Nepenthes, which are designated by gardeners by the name of 

 "pitcher-plants" in the narrow sense. 



The leaves in both the Sarracenias just named are heteromorphic. Some of them 

 have acute linear-lanceolate petioles of a uniform green colour, and not hollowed 

 out; and it is only in the case of from three to five leaves in each individual plant 

 that the petioles are transformed into tubes with infundibuliform enlargements at the 

 top. The rim round the mouth of the funnel is somewhat swollen and doubled down 

 externally; but above the orifice the lamina is arched so as to form a cover to the 

 pitcher. The margin of the leaf of Sarracenia laciniata, which is shown in fig. 21 ', 

 is crinkled and sinuously folded. The cover and also the upper funnel-shaped 

 ■enlargement of the pitcher are very conspicuous on account of the contrast of the 

 colours displayed upon them. The green of the lower part of the pitcher gets 

 paler and paler above, and merges into a pure white, whilst dark-red veins stand 

 ■out from the green and white ground tints, having the effect of a net- work of blood- 

 vessels. At the mouth of the pitcher, and on the under side of the lid, honey is 

 secreted in such abundance that little drops of it are not infrequently to be seen 

 on the swollen rim, and some oozes down into the infundibuliform portion of the 

 pitcher. But at the very spots where the honey occurs there are also innumerable 

 smooth conical cells with their solid apices directed downwards; and these cells 

 become longer the lower their position in the pitcher. When insects, attracted by 

 the gay-coloured lid, and lured on by the honey, come to the mouth of the 

 pitcher and tread upon the parts covered with the sharp slippery papillae, they are 

 drawn into the depths as though by an invisible power. After they have once 

 alighted on the perilous area, every movement and every effort to climb up against 

 the points causes them to slide further and further down towards the bottom of 

 the pitcher, where they are hopelessly lost, being killed within a short time and 

 ultimately decomposed. 



An instance of an exactly similar kind is afforded by Cephalotus follicularis, 

 which has long been known as a plant native on moorlands in eastern Australia. 

 It is allied to saxifrages and currants, and is represented on a scale of half the 



