74 THE CIECULATION OF NITEOGEN IN NATURE. 
more indeed than is required for the fixation of the necessary 
carbon. It was found by Winogradsky that the nitrifying 
bacilli oxidized thirty-five parts of nitrogen whilst they 
assimilated one part of carbon, so providing by one function 
the energy necessar}^ for the performance of the other. 
It is curious to notice that whilst we burn carbon in our 
systems to provide us with the energy necessary amongst 
other things to avail ourselves of the all-important nitrogen 
in our food, the nitrifying bacilli burn nitrogen in order to 
acquire the power of annexing the equally necessary 
carbon. 
