ther. But Mr Huxley
shews, by observation and experiment on _Salpa_ and _Pyrosoma_, that
each has independent powers of reproduction, and his facts are
conclusive against the theory of 'alternation of generations.' The two
generations, as now appears, are not of distinct individuals, but are
both required to make a complete individual. This paper will be sure
to provoke criticism, and perhaps excite further research. Mr Hopkins
has been enlightening the Geological Society 'On the Causes of the
Changes of Climate at Different Geological Periods;' and assigns as
one of the causes, the flowing of the gulf-stream in a different
direction formerly to that which it follows at present, whereby the
northern ice was brought down in great masses to form our glacial
period.

Some of our _savans_ are interested in Professor Simpson's
communication to your Edinburgh Botanical Society, concerning his
experiments on Alpine plants kept covered with snow by artificial
means in an ice-house for several months. He finds that plants and
seeds so treated sprout and germinate rapidly when exposed to the warm
air of spring and summer. It appears also that chrysales similarly
treated become moths in about one-tenth of the time required under
ordinary circumstances; from which facts, and the celerity of
vegetation in Canada and the arctic regions, Professor Simpson infers
that, if we in this country were to keep our grain in ice-houses
during the winter, we should get quicker and better crops, and avoid
the ill consequences which sometimes attend sowing in autumn, or too
early in spring. The subject is novel as well as interesting, to say
nothing of its bearing on agriculture, and we shall be glad to see the
promised results of further inquiry.

There are one or two other Scottish matters which may be mentioned.
One is the discovery by Dr Penny of Glasgow, of potash salts in
considerable quantity in the soot from blast-furnaces. In our iron
districts, and among our iron merchants, it is undergoing that sort of
discussion which savours of profit. Potash salts are so valuable, that
if the discovery can be reduced to economical practice, there is no
doubt that the hitherto wasted and unrecognised substance will be
turned to good account. The other is the 'Platometer,' invented by Mr
Sang of Kirkcaldy, described as a 'self-acting calculator of surface;'
in other words, by using this contrivance, you may get the 'square
measure included within an