Can it be done?
Yes.

It lies in our power, without the least meddling, to see a procession march along a perfect circular track.

I owe this result, which is eminently deserving of our attention, to pure chance.
On the shelf with the layer of sand in which the nests are planted stand some big palm-vases measuring nearly a yard and a half in circumference at the top.

The caterpillars often scale the sides and climb up to the moulding which forms a cornice around the opening.

This place suits them for their processions, perhaps because of the absolute firmness of the surface, where there is no fear of landslides, as on the loose, sandy soil below; and also, perhaps, because of the horizontal position, which is favourable to repose after the fatigue of the ascent.