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 sev- 

 eral 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 experi- 

 ments 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 a toutes les notions que nous avons du 

 feu." They may be further reminded that the writer's own experi- 

 ments 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 be- 

 lief 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 at- 

 tempts 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," 18*73, No. 143, p. 227. 



