152 CONCERNING PEESENT 



and 1879, and recorded in the thesis above referred to, has been 

 induced to put the temperature rather higher. He says, however, 

 that a temperature of 115° C. is sufficient to sterilise all fluids 

 "completely and very rapidly," and therefore to kill any Bacilli 

 spores that may be contained therein. 



No statements as to the lowest temperature at which we may 

 be certain that the spores of Bacilli are killed are made by 

 Fischer ; he says,' however, that superheated steam in an auto- 

 clave "kills the toughest spores in one minute at 140° C." 

 Macfadyen also says,= "No spore, however resistant, remains 

 alive after one minute's exposure to 140° C." 



In reference to the spores of Fungi, de Barry 3 mentions that 

 in their dry state 130° C. has been necessary for their destruction, 

 but he adds " the death-point of the spores of Fungi is often much 

 lower than this in water or watery vapour, and it has not been 

 shown that any can under these circumstances survive a temperature 

 of 100 C." 



I have, however, recorded experiments in which living organisms 

 have been plentifully found in fluids that had been heated within 

 closed vessels to higher points than any of those above mentioned 

 as lethal. 



Thus, experiments were made with neutral and faintly alkaline 

 hay infusions of this nature.* " In each case about half an ounce 

 of the fluid was used, half filling a tube which was sealed when 

 cold ; so that above the fluid there was ordinary air. ... In 

 twenty-one cases they were heated to 248° F. (120° C.) for thirty 

 minutes ; and in iive of these latter trials (all with the same 

 hay infusion) no fermentation subsequently occurred. In the 

 other instances more or less distinct fermentation supervened — 

 though in some the signs of change before opening the vessels were 

 only slight.s , . . Also in five other experiments in which milk was 

 heated to 240° F. (iiS"5° C.) for ten minutes, fermentation more or 

 less marked occurred in each case in from two to ten days." 



The nature of the changes seen in the fluids and the kinds 



' "The structure and Functions of Bacteria," Transln., 1900, p. 76. 



= "Nature," February 7, 1901, p. 361. 



3 "Fungi, Mycetozoa and Bacteria," Transln., p. 347. 



* See a Memoir "On the Conditions favouring Fermentation," "Journ. of 

 Linn. Soc." (Zool.), vol. xiv., pp. 50-53. 



s These tubes on account of their subsequent treatment were necessarily of 

 very thick glass, and were therefore thoroughly ftambh when I prepared them 

 shortly before they were made use of. 



