44 ORIGIN OF LOWEST ORGANISMS. 



All these experiments to which I have been alluding 

 are based upon the supposition (assented to by Pas- 

 teur and Huxley) that Bacteria which pre-existed in 

 the solution would certainly be destroyed by its being 

 raised for a few minutes to a temperature of 212 F. 

 This conclusion is, I believe, perfectly correct,* and in 

 support thereof I will adduce the following additional 

 information. 



Limits of l Vital Resistance' to Heat displayed by 

 Bacteria and Torulcz. 



After stating elsewhere t, that Vibriones are partly 

 broken up or disintegrated by an exposure for a few 

 minutes to a temperature of 212 F. in an infusion 

 which is being boiled, and also that, in all probability, 

 the life of Bacteria would be destroyed by such a 

 treatment, I made the following remarks : " With 

 reference to these organisms, however, one caution is 

 necessary to be borne in mind by the experimenter. 

 The movements of monads and Bacteria may be, and 

 frequently are, of two kinds. The one variety does 

 not differ in the least from the mere molecular or 

 Brownian movement, which may be witnessed in 

 similarly minute, not-living particles immersed in 

 fluids. Whilst the other seems to be purely vital 



* M. Pasteur attempted to make a distinction in the case of 

 slightly alkaline or neutral fluids (loc. cit., pp. 60-65). I have 

 endeavoured to show the untenability of his conclusion in 

 1 Nature,' 1870, No. 37, pp. 224-227. 



f ' Nature,' 1870, No. 35, p. 171. 



