Effect of exposure to liquid air upon the vitality and virulence of the bacillus tuberculosis

A series of experiments carried out early in the year 1900 with the object of testing the effect of the temperature of liquid air upon the vitality and virulence of the bacillus tuberculosis produced results which, although in complete accord as far as the question of vitality was concerned with those arrived at by Professor Macfadyen in the carefully planned experiments reported to the Royal Society on the 1st February and the 5th April, 1900, raised some doubt in my mind as to whether the abnormally low temperature, continued for a lengthened period, might not have some modifying effect upon the virulence of the organism. I decided therefore, in the month of January of this year, to put the question to the test of an experiment which I hoped would be conclusive.