Ridley.—Symbiosis of Ants and Plants. 459 
that except that he noted that ants frequented this plant he had made no 
observations on their action on the plant. 
The BuH’s-horn Thorn, Acacia cornigcra , a native of South America, 
has long been cultivated in the Botanic Gardens, Singapore, from a plant 
sent from England and propagated by cuttings. Naturally the ants which 
normally occupy the hollow swollen stipules did not accompany the plant, 
but a descendant of the original importation was for a considerable time 
occupied by a local species of ant (I believe it was a species I have also found 
in Korthalsia scaphigerd). This ant bored into the stipules and tenanted 
them in much the same way as the South American ant does in the native 
haunts of the Acacia. Unfortunately they have since abandoned the tree, so 
I am unable to make further observations. But the fact serves to show that 
ants are always ready to adopt a place suitable for their nesting, even if it is 
not the class of nesting-place they are accustomed to. 
Korthalsia. 
The genus Korthalsia , to which I pass on next, comprises two sections 
of rattans, in one of which the ligule is developed into a close tight-fitting 
sheath, while in the other the ligule is dilated into a rounded or oblong 
sheath, or ochrea, of a stiff papery texture, and so dilated that it forms an 
ideal place for an ants’ nest when the ants have perforated it so as to make 
an entrance, and this ochrea is commonly so perforated and occupied 
by ants. 
There are two species of this section in the Singapore Botanic Gardens, 
viz. Korthalsia scaphigera , Mart., and K. echinometra , Becc. ; both are 
wild in Singapore also. 
K. scaphigera , Mart., when growing in thick jungle is more slender and 
has narrower leaves and longer and narrower ochreae than the form planted 
or growing naturally in open exposed spots. In the jungle form growing 
in the Gardens forest, I find that the ochreae are tenanted by a small species 
of Camponotus , but by no means all the ochreae are occupied. If one 
on a stem is occupied, usually all the rest, excluding the top one which 
is still covering the base of the bud, are occupied, but only a comparatively 
few stems are inhabited by the ants. Where the plant is planted out in the 
open ground, I find a large proportion of the ochreae are not occupied, and 
the ant at present occupying the ochreae is quite a different one from the 
one in the forest. It is a much larger and broader black ant, with powerful 
mandibles and a remarkably prominent process on the pedicel. Both 
species, however, belong, I believe, to the genus Camponotus. 
In the Korthalsia echinometra , Becc., cultivated in the Gardens, there 
are no ants. Beccari mentions the occurrence of two species of Camponotus 
and one Tridomyrmex in Korthalsia scaphigera , and another Camponotus in 
K. echinometra. It appears to me very probable that no special kind of 
