196 A NATURALIST IN BORNEO 



either in the middle or near the margin, and their 

 position is quite irregular. 



Calamus amplectens is another rattan which harbours 

 ants. The two lower segments of the leaves are folded 

 back and embrace the stem in such a way that it is 

 enclosed by them, very much as a stick held between 

 hands clasped together. 



Nepenthes bicalcarata is one of the most remarkable 

 Pitcher-Plants in the world. It is found climbing up 

 trees, and its stalk is often 20 feet long. The pitchers 

 are of two shapes ; those which grow from the lower 

 leaves are like bladders truncated at the mouth, and 

 their transverse diameter is about equal to their 

 length. The stem of the pitcher is straight, and the 

 pitcher is joined on to it at right angles, its lower 

 end is swollen, hollowed out and perforated. The 

 pitchers springing from the upper leaves are smaller, 

 infundibuliform, and rather constricted at the base. 

 They are attached to the pitcher-stem in a curve, and 

 the stem itself is always twisted into one curl of a 

 spiral. This curl is swollen and hollow, and is per- 

 forated by a single hole. There is no direct evidence 

 that these peculiar cavities are inhabited by ants, but 

 their structure leads me to suppose that this is their 

 purpose, and as glands are found in the tissue of the 

 pitcher-stems, it is quite likely that these serve as 

 nectaries for the ants. 



The species of the genus Pachycentria are all 

 epiphytic, or pseudo-parasitic, and some of them are 

 provided with tuberous swellings on the roots, which 

 are much frequented by ants. These tubers are filled 

 with a spongy tissue, and it is probable that ants 

 destroy this tissue and live inside the tubers. 1 



1 Pachycentria. I have seen many of these, including the 



