In accordance with the will and the design of the architects, who merely stand by and gesticulate, the opposite margins approach, or the apex curls towards the base, or towards one of the sides to form a miniature funnel.  When the extremities are so close that the intervening space may be spanned, threads of white gossamer are laced across, and the slack being taken up by degrees, in a few days a cosy pocket with closely-fitting seams is completed.

How is this folding of the leaf accomplished?  A theory which presents itself is that the ants eject some active chemical principle into certain of the cells of the leaf tissue, and that the stimulus is transmitted by excitation from cell to cell, bringing about a general and uniform contraction without destroying the vitality of the leaf.  Further, by the application of the injection to specific cells the ants convey impulses to specific nerves, causing the leaf to curl longitudinally or laterally, or at any angle they design.  The poison that a single ant injects into the neck of a brawny man so affects his nervous system that he twists and writhes and stamps his feet with energy sufficient to destroy millions of the species.  Maybe a slightly different compound is reserved for vegetable substances, which can offer only a flabby sort of remonstrance.  If this theory be supported on investigation, surely the green tree-ant will deserve to be catalogued among creatures who have solved labour-saving problems—­who employ consciousness, if not rational thought, to compensate for physical frailty.  This theory is applicable to the manipulation of a single leaf only, and of a leaf of considerable size.  Yet these feeble folk more frequently take up their quarters in trees bearing small leaves, of which scores are embodied in a mansion.  Immense and concentrated exertion is necessary to draw far-flung branchlets and leaves together, and the feverish host accomplishes a seemingly impossible feat by an organised combination of engineering with co-operative labour.  Spaces between leaves and twigs four and five inches wide are bridged by chains of ants—­each individual clasping with its mandibles above the abdominal segment its immediate companion; occasionally the ant grips its fellow by the posterior legs, and is so held by the next in order.  In the construction of these chains ants hastily mass at each side of the gulf to be spanned, and crawling, or rather running over each other, form pendant strands, each ant a living link.  The chains sway until the terminal links engage, when they are immediately shortened up.  Several of these chains are swung across parallel to each other with astonishing rapidity; and in addition to the constant strain of the hauling workers at each end they are used as bridges by innumerable other workers and fussy superintendents, the traffic on them being almost as voluminous and bustling as that of a Thames thoroughfare.  Gradually the most obstinate branchlet with its spray of leaves is drawn into juxtaposition