Floney-Producing Caterpillars. 135 
when they are instantly withdrawn. The ants pay no heed 
to the tubes. They seek for nothing from them, and expect 
nothing. But they turn at once to the eleventh, caress the 
back of that segment, and, putting their mouths to its open- 
ing, exhibit an eager desire and expectancy. Suddenly a 
dull green, fleshy, mammilloid organ protrudes, and from the 
summit of which comes a tiny drop of clear green fluid, 
which the ants, some two or three perhaps standing about 
it, lap greedily up. As the drop disappears, this organ sinks 
in at the apex, and is so withdrawn. The ants then run 
about, some in quest of other larve upon the same stem, 
some with no definite object, but presently return and pursue 
the caressings as before. The intervals between the appear- 
ance of the globule vary with the condition of the larva. 
Where exhaustion by long-continued solicitings occurs, some 
minutes elapse before renewal is effected, the tubes in the 
meantime remaining concealed. Fresh larve, however, require 
little or no urging, and globule follows globule, as many as 
six emissions in seventy-five seconds, without even a retract- 
ing of the organ. Often the presence of the ant, when the 
larva is aware of it, evokes, all unsought, the sugary fluid. 
Ordinarily the tubes expand when the ants are absent from 
the last segments, and are certainly withdrawn when they 
come near. These tubes, from all appearances, serve as 
signals to the ants. When the latter discover them expanded, 
they know that a refection is ready, and rush to the opening 
in the eleventh segment where it is to be found. The tubes 
certainly serve no other purpose. No visible duct appears 
in the dome of the tube when largely magnified, and the ants 
seek nothing from it or the twelfth segment. They cannot be 
used to intimidate, or to frighten away enemies, for in the 
younger stages, when the larve have the most to dread, 
neither the tube nor the organ in the eleventh segment is 
available. The outward openings, and the orifice in the 
eleventh segment, exist in the youngest larval stages, but are 
functionless until the larva has nearly attained maturity. 
