473 
Ridley.—Symbiosis of Ants and Plants. 
adenopus as figured in Schimper’s Pflanzengeographie, and their origin 
seems to be of the same nature. I have seen no trace of them anywhere on 
the Macarangas which do not harbour ants in the stems. 
The three distinct myrmecophilous species I have been able to study 
in life are M. hypoleuca , M. triloba , and M. Griffithiana , three very 
abundant plants in and around the Botanic Gardens ; of the last two, indeed, 
I may say there are hundreds of plants of all stages from seedlings to full- 
grown trees. I will now proceed to give a fuller account of each of these 
three species. 
Macaranga triloba, Muell. Arg. 
This is a tree of no great size (usually attaining a height of about 
forty feet) which is common in the low country of the Malay Peninsula, 
occurring in woods usually of secondary growth, or on edges of woods, and 
usually in dry positions (as compared with M. Griffithiana at least, which 
seems to prefer lower lying, permanently damp spots). In secondary jungle 
the trees come up abundantly, often close together. It is absent from the 
original forest, and its presence in any quantity may be taken as a sign that 
the wood in which it grows is of secondary growth. The stem of the 
seedling is always green, and is not covered with the glaucous or white wax 
coating formed on M. hypoleuca and Griffithiana. 
The stem of the plant is hollow and contains almost invariably nests of 
an ant which has been identified by Col. Bingham as Crematogaster near 
C. Daisyi of Forel. I have found stems quite woody and half an inch 
through still occupied by the ants, and it is quite rare to find a plant which 
is not or has not been occupied by ants. 
The first account of the myrmecophily of this plant was published by 
Miss Winifred Smith in the New Phytologist, ii. 79 (1903), Pis. V and VI. 
The material on which this account was based was brought to England by 
Mr. Tansley from the Botanic Gardens of Singapore. It was not, how¬ 
ever, very extensive, and many points in the relations of the ants to the 
plant could not be made by Mr. Tansley for lack of time. The blanks in 
the history, as given in the New Phytologist, I hope to supply in this account 
of the plant. 
The stem of the seedling is at first solid, slender, and woody, con¬ 
taining a small pith, and after it has grown for some inches, the internodes 
above become more succulent and swollen, dilating in the centre, and 
gradually narrowed to the nodes. This, however, is less conspicuous in 
M. triloba than in M. hypoleuca. The stem is smooth and green outside, 
not possessing the glaucous or white coating of wax met with on M. Griff th- 
iana and M. hypoleuca. The terminal internode remains solid for some 
little time, succulent and green ; the swollen internodes are hollow, the pith 
having disappeared. At first it remains as transverse bars, which later break 
