1873.] 



necessary to kill Bacteria,, Vibriones, fyc. 



225 



idea, entertained by some, of the eggs of the lowest infusoria being 

 protected from the injurious influence of the boiling water by reason of 

 their extreme minuteness, was a supposition so improbable as scarcely to 

 deserve serious consideration. Such a notion was, he thought, wholly 

 opposed to what was known concerning the transmission of heat. 

 Whilst, therefore, the opinion of those who believe that eggs have the 

 power of resisting the destructive influence of boiling water could be 

 fully refuted, Spallanzani thought it by no means followed that the 

 infusoria which always, after a very short time, appeared in boiling 

 infusions had arisen independently of the existence of eggs. The 

 infusions being freely exposed to the air, it was very possible that this 

 air had introduced eggs into the fluids, which by their development had 

 given birth to the infusoria*. 



After the lapse of a century it has at last been clearly shown that this 

 supposition of aerial contamination advanced by Spallanzani (warrant- 

 able and natural as it was at the time) is one which, in the great 

 majority of cases, is devoid of all foundation in fact, so far as concerns 

 the organisms essentially associated with processes of putrefaction, viz. 

 Bacteria and Vibriones. The means of proving this statement, based 

 upon independent observations made by Professor Burdon Sanderson and 

 myself, were recently submitted to the consideration of the Eoyal 

 Society f. Before the reading of this communication I was under the 

 impression that almost every one of those who had taken part in the 

 controversies which had been carried on both here and abroad concerning 

 the Origin of Life were prepared to admit, as Spallanzani had done, that 

 the eggs or germs of such organisms as appear in infusions were unable 

 to survive when the infusions containing them were raised to the 

 temperature at which water boils. This impression was produced in 

 part by the explicit statements on this subject that had been made by 

 very many biologists, and also in part by a comparatively recent and 

 authoritative confirmation which this view as to the destructive effects 

 of boiling infusions upon Bacteria had received. Little more than two 

 years ago Professor Huxley, as President of the British Association 

 for the Advancement of Science, recorded experiments in his Inaugural 

 Address which were obviously based upon this belief as a starting-point ; 

 and subsequently, in one of the Sectional Meetings, after referring to some 

 of my experiments, and to the fact that all unmistakably vital movements 

 ceased after Bacteria had been boiled, Professor Huxley addedj : — " I 

 cannot be certain about other persons, but I am of opinion that 



* A few pages further on this view is thus shortly expressed : — " II est evident que 

 toutes les tentatives faites avec le feu, peuvent bien servir a prouver que les animaux 

 inicroscopiques ne naissent point des oeufs que Ton supposait exister dans les infusions 

 avant qu'on leur fit sentir le feu ; mais cela n'empeche pas qu'ils n'aient pu etre formes 

 de ceux qui auront ete portes dans les vases apres 1' ebullition." 



t See Proceedings of Eoyal Society, IS T o. 141, 1873, p. 129. 



\ See Keport in Quart. Journ. of Microscop. Science, Oct, 1870. 



