ANT-SUPPORTING PLANTS. 
35 
are ripe and the leaves are falling they have a singular appear- 
ance. A sort of ant lodges in these thorns in immense quanti- 
ties, and if the tree be shaken ever so little, they fall down like 
a shower of rain and attack the passenger.” The Mimosa 
cornigera of older botanists is now referred to various Acacias, 
such as A . cochliantha , A. macrantha , A. sphceroslachya , A. 
spadigera , and others, all characterised by these large hollow 
thorns. Mr. Belt, in his already-quoted volume, has given so 
many interesting particulars of the relations existing between 
the ants and one of these species, which he calls the “ bull’s- 
horn thorn,” that I shall make no apology for quoting some of 
them, especially as they differ in various points from any other 
account. “ These thorns,” he says, “ are hollow, and are 
tenanted by ants that make a small hole for their entrance and 
exit near one end of the thorn, and also burrow through the 
partition that separates the two horns, so that the one entrance 
serves for both. Here they rear their young, and in the wet 
season every one of the thorns is tenanted, and hundreds of ants 
are to be seen running about, especially over the young leaves. 
If one of these be touched, or a branch shaken, the little ants 
( Pseudomyrma bicolor , Gruer.) swarm out from the hollow 
thorns, and attack the aggressor with jaws and sting. They 
sting severely, raising a little white lump that does not 
disappear in less than twenty-four hours. These ants form a 
most efficient standing army for the plant, which prevents not 
only the mammalia from browsing on the leaves, but delivers it 
from the attacks of a much more dangerous enemy — the leaf- 
cutting ants. For these services the ants are not only securely 
housed by the plant, but are provided with a bountiful supply 
of food ; and to secure their attendance at the right time and 
place, this food is so arranged and distributed as to effect that 
-object with wonderful perfection. The leaves are bipinnate ; at 
the base of each pair of leaflets, on the mid-rib, is a crater- 
formed gland, which, when the leaves are young, secretes a 
honey-like liquid. Of this the ants are very fond, and they are 
constantly running about from one gland to the other to sip up 
the honey as it is secreted. But this is not all ; there is a still 
more wonderful provision of more solid food. At the end of 
each of the small divisions of the compound leaflet there is, 
when the leaf first unfolds, a little yellow fruit-like body, united 
by a point at its base to the end of the pinnule. Examined 
through a microscope, this little appendage looks like a golden 
pear. When the leaf first unfolds the little pears are not quite 
ripe, and the ants are continually employed going from one to 
another examining them. When an ant finds one sufficiently 
advanced it bites the small point of attachment ; then, bending 
down the fruit-like body, it breaks it off and bears it away in 
