Chapter XVI.

1. Land animals have also the same disposition for concealment. For in winter they all hasten to conceal themselves, and appear again when the season becomes warmer. Animals conceal themselves to guard against the excesses of temperature. In some the whole race is concealed; in others only a part of them. All the testacea conceal themselves, as those which are marine, the purpura, whelk, and all that class; but the state of concealment is more conspicuous in those which do not adhere to rocks; for these also conceal themselves, as the pectens. Some have an operculum on their exterior, as the land snails; and the alteration of those that are not free is inconspicuous. They do not all conceal themselves at the same period; for the snails are torpid during the winter, the purpura and whelk for thirty days under the dog star, and the pectens at the same period. Most of them conceal themselves in very cold and very hot weather.

2. Almost all insects become torpid, except those which dwell in the habitations of men, and those that perish and do not survive for a year. They are torpid in the winter. Some conceal themselves for a good while, others only in the coldest days, as the bees, for these also conceal themselves. This is shown by their not touching the food which is prepared for them; and if any of them creep out, they appear transparent, and plainly have nothing in their stomach. They remain at rest from the setting of the Pleiades until the spring. Animals pass their torpid state in warm places, and in the spots they are accustomed to inhabit.