478 
Ridley. Symbiosis of Ants and Plants. 
Macaranga hypoleuca, Muell. Arg. 
This tree is much larger than the other two species, attaining a height 
of nearly 60 feet, with a stout, grey, smooth stem about 36 to 42 inches 
round. 
It has a much larger spreading head of foliage. The leaves are stiff 
and coriaceous when adult, and conspicuously white on the back, with 
a coating of white wax in the form of an easily detached powder, which 
under a low power of the microscope is seen to consist of small bodies 
of the shape of curved sausages. 
The tree inhabits rather drier spots than M. Griffithiana , borders 
of woods and secondary forests. 
The seedling is curiously dilated between the nodes, narrowing to the 
node at both ends. Though this occurs in the other species it is not 
so conspicuous in them as in Macaranga hypoleuca. The internodes are 
hollow, and usually tenanted by ants in the same way as the other species, 
and in the hollows occurs what appears to be the same species of coccid. 
The young leaves are at first woolly and have their three lobes deflexed ; 
as they expand they become glabrous, and at length develop a white waxy 
coating. Their margins bear nectaries, as do those of the other two species, 
but these are larger and more brightly coloured. They first appear as 
crimson polished cups on the nerve endings. They gradually lengthen 
as the leaf grows, and become club-shaped with the depression on the one 
side of the club ; when the leaves become fully developed and coriaceous 
they disappear, as already described. On the under side of the young leaf 
are abundance of bladder-glands similar to those of the other species, and 
scattered about between the raised nerves are a number of food-bodies, 
white and globular. These are most plentiful in plants which are not pro¬ 
tected by ants. The ants in plants occupied by them spend much of their 
time beneath the deflexed blade of the young leaf, and are as unwilling to 
quit as those that frequent the deflexed bud-bracts of the M. triloba are to 
quit the bud-bracts. I have seen them running about with the food-bodies 
in their mouths. 
Beneath the shelter of the leaf also live acari, which seem to be harmless 
to the plant and undisturbed by the ants. In nearly adult leaves, before 
the coating of white wax is fully developed, the whole of the surface of the 
under side except the nerves is thickly dotted over with bladder-glands, and 
food-bodies are to be seen here and there on the sides of the raised nerves, 
especially in the angles formed by the branching of the nerves. The bud- 
bracts are lanceolate acuminate erect leaves, with a low keel on the back, 
pale green in colour, with a scanty thin deposit of wax and some brown 
hairs, but no glands. 
