e passage its
two closed mandibles, whose points project a little way outside; then,
opening them to a definite radius, like a pair of compasses, it widens
the aperture and makes it regular.

I imagine, without venturing, however, to make a categorical statement,
that the perforated apex is a chimney to admit the air required for
breathing. Every pupa breathes in its shell, however compact this may
be, even as the unhatched bird breathes inside the egg. The thousands
of pores with which the shell is pierced allow the inside moisture to
evaporate and the outer air to penetrate as and when needed. The stony
caskets of the Bembex- and Stizus-wasps are endowed, notwithstanding
their hardness, with similar means of exchange between the vitiated and
the pure atmosphere. Can the shells of the Anthidia be air-proof, owing
to some modification that escapes me? In any case, this impermeability
cannot be attributed to the excremental mosaic, which the cocoons of the
resin-working Anthidia do not possess, though endowed with an apex of
the very best.

Shall we find an answer to the question in the varnish with which the
silken fabric is impregnated? I hesitate to say yes and I hesitate to
say no, for a host of cocoons are coated with a similar lacquer though
deprived of communication with the outside air. All said, without being
able at present to account for its necessity, I admit that the apex of
the Anthidia is a breathing-aperture. I bequeath to the future the task
of telling us for what reasons the collectors of both cotton and resin
leave a large pore in their shells, whereas all the other weavers close
theirs completely.

After these biological curiosities, it remains for me to discuss the
principal subject of this chapter: the botanical origin of the materials
of the nest. By watching the insect when busy at its harvesting, or else
by examining its manufactured flock under the microscope, I was able to
learn, not without a great expenditure of time and patience, that the
different Anthidia of my neighbourhood have recourse without distinction
to any cottony plant. Most of the wadding is supplied by the Compositae,
particularly the following: Centaurea solsticialis, or St. Barnaby's
thistle; C. paniculata, or panicled centaury; Echinops ritro, or
small globe-thistle; Onopordon illyricum, or Illyrian cotton-thistle;
Helichrysum staechas, or wild everlasting; Filago germanica, or common
cotton-rose. Next come the Labiatae: