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XXXVII. Suggestion as to a possible Source of the Energy 

 required for the Life of Bacilli, and as to the Cause of their 

 small Size. By G. Johnstone Stoney, M.A., D.Sc, 

 F.R.S., Vice-President, Royal Dublin Society *. 



IN that part of the material universe which man's position in 

 time and space, and the limitations of his senses, permit 

 him to investigate, the Dissipation of Energy is so prevalent 

 that instances of the reverse process can seldom be clearly 

 traced out, though many such can be dimly seen. Under 

 these circumstances, even possible instances, such as that dealt 

 with in this paper, are instructive if they are of a kind to be 

 fully understood. They are also important, for if the universe 

 is permanent, there must be, or have been, or be about to 

 be, parts of the universe where the Concentration of Energy 

 is as largely predominant as its dissipation is within our 

 experience. 



Some bacilli, e. g. some of the nitrifying bacilli of the soil, 

 are said to be sustained by purely mineral food, while they 

 furnish ejecta which contain as much potential energy as the 

 food, or more. If this be the case, they must be supplied 

 with a considerable amount of energy to enable them to evolve 

 protoplasm and the other organic compounds of which they 

 consist, from these materials. Now many bacilli are so 

 situated that this energy is certainly not obtained from sun~ 

 shine, and it is suggested that it may be derived from the 

 gases or liquids about them. 



The average speed with which the molecules of air dart 

 about is known to be nearly 500 metres per second — the 

 velocity of a rifle-bullet ; and the velocity of some of the 

 molecules must be many times this, probably five, six, or 

 seven times as swift. We do not know so much about the 

 velocities of the molecules in liquids as of those in gases, but 

 the phenomenon of evaporation and some others indicate that 

 they are at least occasionally comparable with those of a gas. 

 Accordingly, whether the microbe derive a part of its oxygen 

 or other nourishment from the gases, or from the liquids about 

 it, it is conceivable that only the swifter moving molecules 

 can penetrate the microbe sufficiently far, or from some other 

 cause are either alone or predominantly fitted to be assimi- 

 lated by it. 



Now if this be what is actually taking place, the adjoining- 

 air or liquid must become cooler through the withdrawal from 



* From the Scientific Proceedings of the Royal Dublin Society, 

 vol. yiii. part i. Communicated by the Author. 





