CARNIVOROUS PLANTS 87 



In the " pitcher-plants " the leaves take the form of 

 upright pitchers. The upper part secretes honey, which 

 attracts numerous insects. Below this zone is a slippery 

 surface, the slide-zone, which causes the insects to fall into 

 the next the zone of hairs. These hairs are inclined down- 

 ward, so that they catch and prevent the insects from climb- 

 ing out, and they are drowned in the water at the bottom 

 of the pitcher where they decompose and provide food for 

 the plant. 



It has been said that a further adaptation takes place 

 in one species of pitcher-plant (Nepenthe bicalcarata). The 

 species occurs in Borneo, where a little lemur (Tarsius spec- 

 trum) has learned that it can get a number of insects from 

 a pitcher-plant without the- trouble of catching them for 

 itself. This particular pitcher-plant has got the better of 

 the lemur, however, for it grows two long strong prickles 

 from the lower side of the base of the lid. These project 

 downwards into the opening of the pitcher, so that the 

 would-be robber is seriously scratched. 1 



The manner in which some other carnivorous plants 

 catch their prey is equally remarkable. The leaves of 

 Drosera are provided with numerous tentacles, at the ends 

 of which are glandular enlargements. The tentacles round 

 the margin of the leaf are long, those in the middle are 

 short. The glands secrete a quantity of a glistening and 

 very sticky substance, which insects mistake for dew or 

 honey and are attracted. Now if the short central tentacles 

 are stimulated, all the long peripheral tentacles bend over 

 so that their enlarged ends cover the middle of the leaf. 

 If an individual long tentacle is stimulated, only that par- 

 ticular tentacle moves. Let us see what happens when an 

 insect touches any of the tentacles of a leaf. If it touches 

 the central tentacles, it is held by the sticky substance, and 

 all the long peripheral tentacles bend over and enclose it. 

 If it touches one of the long peripheral tentacles, it is also 



1 Quoted by P. Geddes in Chapters in Modern Botany, \>. 26, Murray, 

 London, 1893. 



