After a sweat gland squirts, it takes about 9 seconds for that sweat gland to fill up and squirt again.
How the north was won
How the north was won New evidence from researchers studying primeval
forest ecology on Axel Heiberg Island in the Canadian Arctic has
given scientists a good idea of how pine trees drove redwoods from
the forests they once inhabited. The evidence comes from a large
area of preserved specimens of an ancient forest located on the
island. More than 40 million years ago the Arctic was much warmer
and it contained forests made up of temperate species such as
redwoods. The warmth came mainly from warm ocean currents. Now the
area is much colder with a tundra environment, and trees like pine
dominate. Researchers say that between 40-35 million years ago, the
environment started to change, resulting in a cooling of the
climate and a change in distribution of plant species. They believe
that factors such as colder ocean currents and geographical changes
contributed to the shift from a temperate to tundra environment.
Recent results also indicate that a root fungus which provides
essential nutrients to many plants may have been unable to function
in the colder temperatures, resulting in the plants dying off. The
researchers theorize that only the plants who depended on fungus
that could function in the cold temperatures survived. 20 JUNE 1998, P. 34-37
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