her species, as if to express the infinite conceptions of that power above her, which "spake and it was done, which commanded and it was brought forth." From the fossilized plants of Atanekerdluk--a flora rich in species and wonderfully preserved in type--and the Miocene flora of Spitzenburg, to the southernmost limits of vegetation on the globe, science has reached out her hands for materials, and gathered them with as much success as avidity. And all scientific botanists agree in referring these fossilized forms from the high northern latitudes, to the Miocene period--one so remote that we can form no adequate conception of it, except as time may be measured by geologic periods. And these materials show that varieties of the _Sequoia_, the tulip-tree, oaks, beeches, walnuts, firs, poplars, hazelnuts, etc., etc., all flourished in these sub-arctic regions during the far-distant period we have named. Many of them must have grown on the spot where their trunks are now to be found, as their roots remain undisturbed in the soil, as well as at a time when these regions enjoyed a warm or cold temperate climate. Many of these fossilized and carbonized forms are identical with the living species of to-day, conclusively showing that neither natural variation, nor any secondary causes, have worked out any changes capable of being scientifically expressed in genetic value. There is also abundant evidence to show that many of the present tropical forms flourished in central and southern Europe as far back as the warm inter-glacial epoch in the Eocene period. And if these inter-glacial periods occurred at the lowest minimum limits of eccentricity in the earth's orbit, as calculated by Leverrier's formulæ, we can have no conception whatever of the length of time actually intervening the period named and our present era. Mr. Croll has given us the limits of highest glaciation covering the last three million years, and shows that there have been but two periods of superior eccentricity in that time, and can be only one in the next million years, with but two or three intervening maxima and minima that may, or may not have been, of any special value. It is true that he assigns importance to these maxima, as affecting possible glaciations, but there are other eminent astronomers and physicists who differ from him, and really attach little or no importance to these of any other intervening periods of eccentricity. If Mr. Croll is correct in his theory and estimates, we must separate these superior glacial epochs by an interval of not less than one million seven hundred thousand years; and nearly three of these periods must have intervened since some of the present tropical forms flourished in Europe. And if these forms have undergone no specific change in all this time, how many years will it require to work out even _one_ of Mr. Darwin's many evolutional changes?