Growth under Vita Glass

Abstract

White rats reared from the age of 30 days to 275 days under vita glass, and properly fed, do not grow at a different rate from those reared under ordinary glass.The offspring of these rats, kept in the same environment, grow at the normal rate when compared with controls born and reared under ordinary window glass.A short discussion of these results is given in the text.Addendum. The temptation to use an artificial source of ultra-violet rays having proved irresistible, a further experiment was performed with 20 males, 10 under vita glass and 10 under window glass. These were exposed to the radiation of a Hanovia quartz mercury vapour lamp on alternate days, at a distance of four feet from the burner. The growth curves are shown on Chart V, and the lengths of exposure have been entered on this chart: it will be seen that the results are the same as with natural sunlight.