Page:Popular Science Monthly Volume 6.djvu/203

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THERMAL DEATH-POINT OF LIVING MATTER.
191

which the experiments were not originally destined to illustrate, and which is, moreover, contradicted by other less equivocal evidence, as to the very existence of which those who adopt this course take care to say nothing. This is a kind of treason to Science of which I hope the future may prove less prolific than the past has been.

And, if we turn now to the specific statements made by those who profess to believe that Bacteria and their germs are able to resist the influence of boiling water, we discover in the first place that all who advance such suppositions find it convenient to pass unnoticed the several series of experiments by which it has been proved that Bacteria and their germs are uniformly killed by an exposure to 140° Fahr. for five minutes. My opponents find it most convenient to take no notice of these experiments, though no one has as yet attempted to dispute their cogency. They prefer to talk vaguely, as though these experiments had never been made, and to adduce various theoretical reasons whose validity they do not attempt to test experimentally. To do this, indeed, would be a vain attempt, because they must be aware that such suppositions as they advance are opposed to generally-accredited scientific doctrines, even if they have not already been specifically refuted.

The suppositions principally dwelt upon may be ranged under three categories:

(a.) It is assumed by some that the mere minuteness of the germs of Bacteria may serve to protect them from that destructive influence which heat exercises upon living matter generally.[1] This is an old objection entirely unsupported by facts, and those who dwell upon it may be reminded that it was unhesitatingly rejected by the former chief of their school, Spallanzani, who said, "Un raisonnement de cette sorte est absolument contraire à toutes les notions que nous avons du feu." They may be further reminded that the writer's own experiments absolutely meet this objection, since they refer to the death-point of invisible germs of Bacteria just as much as to the death-point of those which are visible.[2]

(b.) Others, without definitely committing themselves to the belief that Bacteria-germs can resist the destructive influence of boiling water when they are immersed in it, affect to believe that some germs may have escaped its influence by being "spurted" out of the fluid on to the sides of the glass when the process of boiling commenced. How any such germs could escape the moistening and destructive influence of the hot steam with which they would still be in contact

  1. Some of those who rely upon this supposed reason have resorted to direct attempts to ascertain the death-point of the germs of other organisms, although their results have been, in part, vitiated by the evaporation of the drop of fluid employed, so that the organisms were subsequently exposed to the higher degrees of heat in a dry state.
  2. See "Proceedings of Royal Society," 1873, No. 143, p. 227.