Numerous Lamellicorn And Heteromerous Insects, The
Latter Remarkable For Their Deeply Sculptured Bodies, Were
Slowly Crawling About; While The Lizard
Tribe, the constant
inhabitants of a sandy soil, darted about in every direction.
During the first eleven days, whilst nature
Was dormant, the
mean temperature taken from observations made every two
hours on board the Beagle, was 51 degs.; and in the middle of
the day the thermometer seldom ranged above 55 degs. On the
eleven succeeding days, in which all living things became so
animated, the mean was 58 degs., and the range in the middle
of the day 7 between 60 and 70 degs. Here, then, an
increase of seven degrees in mean temperature, but a greater one
of extreme heat, was sufficient to awake the functions of life.
At Monte Video, from which we had just before sailed, in
the twenty-three days included between the 26th of July
and the 19th of August, the mean temperature from 276
observations was 58.4 degs.; the mean hottest day being
65.5 degs., and the coldest 46 degs. The lowest point to
which the thermometer fell was 41.5 degs., and occasionally
in the middle of the day it rose to 69 or 70 degs.
Yet with this high temperature, almost every beetle, several
genera of spiders, snails, and land-shells, toads and
lizards were all lying torpid beneath stones. But
we have seen that at Bahia Blanca, which is four degrees
southward and therefore with a climate only a very little
colder, this same temperature with a rather less extreme
heat, was sufficient to awake all orders of animated beings.
This shows how nicely the stimulus required to arouse hybernating
animals is governed by the usual climate of the
district, and not by the absolute heat.
Enter page number
PreviousNext
Page 149 of 776
Words from 39690 to 39988
of 208183
