234 BACTERIOLOGY. 



easily or with more difficulty or not at all, 

 since by altering the conditions the nature and 

 amount of the resistance may be changed. 

 This quantitative conception of conditions was 

 first set forth by me at the Naturalists' Meet- 

 ing in Nuremberg in 1893, and Mach at the 

 same time showed that the constancy of con- 

 ditions is full of significance likewise for the 

 constancy of physical processes. 



The Liberation of Energy. 



If the conversion of cause into effect, of poten- 

 tial energy into kinetic energy is prevented by 

 any sort of resistance, such conversion can 

 obviously take place only if this resistance is 

 removed. This process may be called, with 

 R. Mayer, the liberation of energy, and the 

 external forces which accomplish this are 

 called liberating impulseSo I have shown that 

 we cannot content ourselves with neglecting 

 these liberating impulses as of minimal amount, 

 but that they are connected in a definite and 

 quantitative way with the liberation of energy ; 

 the impulse must always introduce energy 

 enough to overcome the resistance. 



All changes of one form of energy into an- 

 other are visible or invisible movements, and 

 the impulses that set free the energy are like- 



