This is the point of view of the majority of astronomers and it seems well taken. Yet many astronomers who have made a special study of the lunar surface for years under all conditions of illumination and phase, and have most carefully observed and mapped and photographed its characteristic markings, are agreed that there are evidences that changes are taking place on the moon, and recently Prof. W. H. Pickering has expressed the belief, substantiated by drawings, that there is a progressive change of color or darkening within certain lunar craters with the advance of the lunar day, indicating, in his opinion, a rapid vegetational growth that springs up in the height of the lunar day and dies out as the lunar night approaches. Some years ago certain selenographers suggested that there might exist in the numberless crater-pits and craters, in the deep-lying _maria_ or "seas," and in the clefts and rills and cracks that form intricate systems all over the lunar surface, certain exhalations from the surface and heavy vapors including possibly carbon dioxide and water vapor to temper the extremes of the long lunar days and night and furnish the necessary medium for the support of certain forms of animal and vegetable life. Many astronomers, including a number who are not in sympathy with the above view, believe that snow and ice exist on the moon, even though water in the form of liquid and vapor is not observable. All the extremely brilliant portions of the surface, according to some astronomers, are covered with snow and ice. Certainly, some portions of the moon's surface reflect sunlight as brilliantly as if they were covered with freshly fallen snow, while other portions appear to be black by contrast. There also appears to be evidence that certain small markings, described as crater-cones and resembling our terrestrial volcanoes more than any other lunar feature, are at times temporarily obscured from view by a veil of vapors. Many observers believe that these crater-cones are active volcanic vents, and that there is considerable volcanic activity still taking place upon the moon.