INFLUENCE OF TEMPEEATURE 55 



by their discoverer Bacterium Ludwigi and Bacillus Ilidzensis capsu- 

 latus were found, which apparently could develop only when the 

 temperature rose above 50° C. The range of temperature is therefore 

 very variable. Some, like Bacterium Ludwigi and Bac. Ilidzensis 

 capsulatus, begin at 50° C, others, isolated in garden soil, were found 

 by Globig to have a range from 15° C. to G8° C. in which develop- 

 ment could take place. One garden-soil species seemed to grow only 

 when the temperature got near 60° C. The maximum temperature of 

 growth yet observed is that given for Bac. thermophilus, viz. 72° C. 

 Eor others the maxima range from 55° 0. to this temperature. 



The following table shows the length of time which is necessary to 

 prevent the development of soil bacteria when placed in water at 

 100° C. and 80° C. respectively : 



Spores Bac. tumescens, 



,, cohaerens, 



,, simplex, 



,, mycoides, - 



,, pumilis, 



,, fusiformis, 



,, carotarum, 



,, Ellenbachensis, - 



, , graveolens, 



,, subtilis, 



,, ruminatus, 



Roughly speaking, it requires at least 60 times as long at 80° C. as 

 at 100° C, so that in sterilising spores, care should be taken to see that 

 the temperature does not fall below the boiling point. In the case of 

 organisms which do not form spores, among which, fortunately, are 

 found the bacilli of diphtheria, consumption, typhoid fever, and most 

 other pathogenic species, the resistance to a temperature of 80° C. is 

 not great. In the case of Sarcina ureae, the following results were 

 obtained after 5 seconds, 10, 15, 20, and 30 seconds respectively 



at 80° C. : 



5-H, 10 + , 15-I-, 20-, 30-. 



( + indicates growth, and -absence of growth.) 



The vegetative cells of the same species, when subjected to 100° C, 

 gave the following results : 



5secs. +, 10 sees. + , 15secs. -I-, 30 sees. -. 



