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of the weather, but he could protect himself by artificial means from 
its extreme influences—whilst plants were exposed to all its changes 
—and it was of great importance to become acquainted with the 
causes that so materially affected their constitution. He then, by the 
aid of maps and diagrams, pointed out the principles on which the 
science of meteorology is founded, and gave a description of the phy- 
sical and chemical constitution of the atmosphere, showing the two 
great currents that are constantly flowing from the equator to the poles 
set up by the action of the sun on the surface of the earth between the 
tropics—which, modified by the diurnal and annual rotation of the earth, 
and by the relative distribution of the sea and land, gave rise to every 
variety of climate. Although the whole of organic nature is depen- 
dent on these phenomena, yet meteorology and botany had been cul- 
tivated as distinct sciences, and it had been reserved to M. Humboldt 
to draw out a general plan, indicating the direct bearing that climate 
had on vegetation. He divided each hemisphere into seven belts or 
zones of climate, each of which contained species peculiar to itself. 
The vegetation of mountains presents on a small scale the image of 
that of the earth considered as a whole. The annual mean tempera- 
ture of a place is not, however, the only circumstance which deter- 
mines its peculiar vegetation. The effects of the lowest temperature 
of winter, as well as the highest temperature of summer, have also to 
be taken into consideration. Besides the vivifying influence of heat, 
the chemical action of the sun’s rays of light modify many of the con- 
_ stituents of a plant. Lastly, he drew attention to the conditions of 
the atmosphere which appeared to affect the health of plants. Blights 
in the wheat and in the potato, and mildew on the grape, had appeared 
simultaneously with great electrical disturbances of the atmosphere ; 
but although the subject was involved in great obscurity a more ear 
nest spirit of observation was at present awakened, and no doubt 
valuable resuts would follow. 
A few Remarks on Cotyledon Umbilicus. 
A communication from Mr. Gissing, of Worcester, was then read, 
entitled ‘ A few Remarks on Cotyledon Umbilicus.’ 
“IT believe that a work on the popular uses of British plants among 
the lower classes of the English people, would prove both useful and 
instructive. Among other classes, it would, I think, exhibit the fact 
that in many of the new remedies introduced into medicine, the prac- 
tice of the village doctress has furnished the first hint to the supposed 
discoverer of new virtues in various plants. 
