58 ANTS AS TREE-GUARDS. 
eaten by herbivorous mammalia. Delpino mentions 
that on one occasion he was gathering a flower of Clero- 
dendrum fragrans, when he was himself ‘suddenly 
attacked by a whole army of small ants.’! 
Moseley has also called attention? to the relations 
which have grown up between ants and two ‘curious 
epiphytes, Myrmecodia armata and Hydnophytum 
formicarum. Both plants are associated in their 
growth with certain species of ants. As soon as the 
young plants developa stem, the ants gnaw at the base 
of this, and the irritation produced causes the stem to 
swell; the ants continuing to irritate and excavate 
the swelling, it assumes a globular form, and may 
become even larger than a man’s head. 
‘The globular mass contains within a labyrinth of 
chambers and passages, which are occupied by the ants 
as their nest. The walls of these chambers and the 
whole mass of the inflated stem retain their vitality 
and thrive, continuing to increase in size with growth. 
From the surface of the rounded mass are given off 
small twigs, bearing the leaves and flowers. 
‘It appears that this curious gall-like tumour on 
the stem has become a normal condition of the plants, 
which cannot thrive without the ants. In Myrmecodia 
armata the globular mass is covered with spine-like 
excrescences. The trees I referred to at Amboina had 
these curious spine-ccvered masses perched in every 
) Scientific Lectures, p. 23. 
2 Notes by a Naturalist on the ‘Challenger,’ p. 389. 
