New Biological Effect of the Gases of the Helium Group.

The mold Neurospora crassa ATCC 5297a was grown in gaseous environments of helium, neon, argon, krypton, xenon, or nitrogen containing approximately 5 percent oxygen. A close correlation of the growth rate R (in millimeters per hour at 30 degrees C) with the molecular weight MW of the chemically inert gas was observed. This correlation is described by the empirical equation: R = 3.88 - 0.1785 (MW).