The air which we breathe is loaded
with impalpable dust that awaits, for ages perhaps, proper conditions
of heat and moisture to give it an ephemeral life that it will lose and
acquire by turns.
In 1707, Spallanzani found it possible, eleven times in succession, to
suspend the life of rotifers submitted to desiccation, and to call it
back again by moistening this organic dust with water. A few years
ago Doyere brought to life some tardigrades that had been dried at a
temperature of 150 deg. and kept four weeks in a vacuum. If we ascend the
scale of beings, we find analogous phenomena produced by diverse causes.
Flies that have been imported in casks of Madeira have been resuscitated
in Europe, and chrysalids have been kept in this state for years.
Cockchafers drowned, and then dried in the sun, have been revived after
a lapse of twenty-four hours, two days, and even five days, after
submersion. Frogs, salamanders, and spiders poisoned by curare or
nicotine, have returned to life after several days of apparent death.
Cold produces some extraordinary effects. Spallanzani kept several frogs
in the center of a lump of ice for two years, and, although they became
dry, rigid, almost friable, and gave no external appearance of being
alive, it was only necessary to expose them to a gradual and moderate
heat to put an end to the lethargic state in which they lay.
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