[11] Recently, by means of photography with short-length light waves, the bacteria of “Foot-and-mouth disease,” invisible to the highest power microscope, have been revealed as rods about 100 submicrons (_i.e._ O.1 micron, or O.0001 millimeter) in length. (_cf._ _Science_, May 30, 1924, Supplement X.) Germs of this dimension could be as easily transported by radiation as the alleged electrically charged stardust in the aurora borealis. It may be of interest, however, to note, in this connection, that the most recent theory of the aurora borealis discards stardust in favor of nitrogen snow. Lars Vegard, a Norwegian professor, ascribes the peculiar greenish tint in the Northern Lights to the action of solar radiations on nitrogen snow, which he assumes to exist at an altitude of more than 60 miles above the earth. When he condensed crystals of solid nitrogen on a copper plate by freezing with liquid hydrogen, he found that these crystals, after bombardment with cathode rays, emit a light of green color, which gives the same strong green spectrum line as the spectrum of the aurora. As the solid nitrogen evaporates, it begins to emit the reddish light characteristic of nitrogen gas. This phenomenon would explain the changes of color that occur in the aurora borealis. (_cf._ _Science_, April 18, 1924, Suppl. X.) Arrhénius’ theory, however, that “life is an eternal rebeginning” explains nothing and leaves us precisely where we were. In the metaphysical as well as the scientific sense, it is an evasion and not a solution. To the logical necessity of putting an end to the retrogradation of the subalternate conditions, upon which the realities of the present depend for their actual existence, we have already adverted. Moreover, the reasons which induce the scientist to postulate a beginning of life in our world are not based on any distinctive peculiarity of that world, but are universally applicable, it being established by the testimony of the spectroscope that other worlds are not differently constituted than our own. Hence Schäfer voices the general attitude of scientific men when he says: “But the acceptance of such theories of the arrival of life on earth does not bring us any nearer to a conception of its actual mode of origin; on the contrary, it merely serves to banish the investigation of the question to some conveniently inaccessible corner of the universe and leaves us in the unsatisfactory condition of affirming not only that we have no knowledge as to the mode of origin of life—which is unfortunately true—but that we never can acquire such knowledge—which it is to be hoped is not true. Knowing what we know, and believing what we believe, ... we are, I think (without denying the possibility of the existence of life in other parts of the universe), justified in regarding these cosmic theories as inherently improbable.” (Dundee Address of 1912, cf.