Note 11 — Chapter I · THE ORIGIN OF LIFE (continued 2)

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.)