CHAPTER VIII 



THE THERMAL DEATH-POINT OF SUCH ORGANISMS 

 AS HAVE BEEN FOUND IN THE TUBES 



AN exposure for a minute or two in fluids to tem- 

 peratures of 60-70 C. is generally admitted to 

 be destructive of Torulae and all non-sporing 

 forms of Bacteria. 



All ordinary sporing forms of Bacilli are ca- 

 pable of resisting higher temperatures, owing to 

 the greater resisting power of their spores. It 

 is, however, generally admitted that these (whether 

 visible or so minute as to be invisible) are killed 

 in fluids when exposed for a few minutes to a 

 temperature of 115 C. 



There are certain extraordinary forms of Bacilli 

 the so-called " Thermophilic Bacteria," found in 

 soils whose spores are capable of resisting still 

 higher temperatures. But, seeing that these have 

 never been met with even in tap-water, and are 

 still less likely to be found in distilled water, or 

 in either of the chemicals that I have employed, 



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