ANT-SUPPORTING PLANTS. 
37 
a small petiole, furnished with hairs, which is hollowed out into 
a groove in its upper surface, and is convex below ; the two 
sides of which swell and enlarge, forming a double heart-shaped 
bladder. This bladder corresponds with two holes, which are 
placed on the under side of the base of each leaf, between the 
two intermediate nerves. It is by these two holes that the 
ants enter and go out of both divisions of this bladder ; and as 
the stems are hollow, the ants enter them by different openings 
which they make in them. It is to this that the plant owes 
the name nid de fourmis , which has been bestowed upon it by 
some of the natives, for it is always, so to speak, covered with 
these insects.” This singular arrangement has not escaped the 
notice of Mr. Belt, who observed similar Meiastomaccce at 
Para and in Northern Brazil. He says : 44 Every pouch was 
occupied by a nest of small black ants ; and if the leaf w 7 as 
shaken ever so little, they would rush out and scour all over it 
in search of the aggressor. I must have tested some hundreds 
of leaves, and never shook one without the ants coming out, 
excepting one sickly-looking plant at Para. In many of the 
pouches I noticed the eggs and young ants, and in some I saw 
a few dark-coloured coccidce or aphides ; but my attention had 
not been at that time directed to the latter as supplying ants 
with food, and I did not examine a sufficient number of pouches 
to determine whether they were constant occupants of the nests 
or not ; but my experience since with the Cccropict trees would 
lead me to expect that they were. If so, we have an instance of 
two insects and a plant living together, and all benefited by the 
companionship. The leaves of the plant are guarded by the 
ants ; the ants are provided with houses by the plant, and food 
by the coccidce or aphides ; and the latter are effectually pro- 
tected by the ants in their common habitation.” The structure 
of the bladder in the other Melastomaceous genera named 
differs but slightly from that of Tococa guianensis ; in some it 
forms part of the leaf, while in others it is somewhat separated 
from it ; it varies in form between round, oblong, and heart- 
shaped, as may be seen from the accompanying figures. Mr. 
Trail, who is at present investigating this subject, writes from 
Santarem to Dr. Hooker (who has kindly lent me his letter), 
that at least three species of ant inhabit a Melastomaceous plant, 
which he believes to be Myrmidone formicaria. He says : 
44 The leaves of the Myrmidone frequently bear hardly any trace 
of the bullae, even on the same twig on which occur largely- 
developed bullae ; ants are usually to be found in them, but not 
by any means constantly, while sometimes they are taken pos- 
session of by solitary bees and wasps.” Of another Melastomacea 
he writes : 44 Of it I have only as yet seen two bushes ; on one 
of them every bulla was tenanted by ants ; on the other not 
