Further, assuming this
luciferous element to be not equally diffused through space, we find a
reason why in some ages of the earth's history the heat should have
been greater than at others, why stars have been seen to vary in
brightness, and why there was that puzzle to geologists--a glacial
period. During that period, according to Mr Nasmyth, with whose words
I finish this part of my communication, 'an arctic climate spread from
the poles towards the equator, and left the record of such a condition
in glacial handwriting on the mountain walls of our elder mountain
ravines, of which there is such abundant and unquestionable evidence.'
Our Microscopical Society have made a discovery in an all but
invisible subject: they now state the _Volvox globator_ to be a
vegetable, and not, as has long been supposed, an animal, as its
cells, presumed to be ova, are produced in the same way as in certain
kinds of _algae_. In the discussion excited by this announcement, it
came out that several other minute forms, classed by Ehrenberg among
living animalcules, are in reality vegetable; which, if true, shews
that a good deal of microscopical work will have to be done over
again.
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