The appearance of extraordinary spots on the sun has attracted a more than ordinary degree of attention to that luminary, and to Mr J. Nasmyth's 'views respecting the source of light,' which, though published a few months since, are now again talked about. Mr Nasmyth, after several years' observation, comes to the conclusion, 'that whatever be the source of light, its production appears to result from an action induced on the _exterior surface_ of the solar sphere;' and he believes it reasonable to 'consider the true source of the latent element of light to reside, _not in the solar orb_, but in space itself; and that the grand function and duty of the sun is to act as an agent for the bringing forth into vivid existence its due portion of the illuminating or luciferous element; which element he supposes to be diffused throughout the boundless regions of space, and which in that case must be perfectly exhaustless. 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. The Syro-Egyptian Society, too, have heard something relating to the same subject--a paper on Ehrenberg's examination by the microscope of the anciently deposited alluvium of the Nile, from which it appears that 'microscopic animals' in countless numbers were the cause of the remarkable fertility of the soil, and not vegetable or unctuous matters. Talking of deposits reminds me of a little fact which I must not forget to mention--the finding of a fossil reptile in the 'Old Red' of your county of Moray is, barring the alarm, as much a cause of astonishment to our geologists, as was the mark of the foot on the sand to Robinson Crusoe.