METABOLISM OF ORGANISMS 45 



But obviously this chain of events must sooner or later come to 

 an end through the dissipation of energy brought about by the 

 metabolic processes of the colorless plants and animals. Sooner or 

 later the supply of potential energy stored up in the chemical 

 compounds of the hay will have become nearly or completely ex- 

 hausted — transformed into the kinetic form and expressed in 

 the life activities of the plant and animal population. 



Thus, after a few weeks, the hay infusion world has reached a 

 standstill — extermination faces the population and inevitably 

 occurs unless microscopic green plants, close relatives of Proto- 

 coccus, find opportunity to develop in the energy-exhausted en- 

 vironment and proceed to entrap the kinetic energy of sunlight, 

 store it up in carbohydrates and proteins, and thus restore energy 

 in the potential form to the hay infusion. 



If such occurs, the hay infusion world is a microcosm indeed 

 — green plants, colorless plants, and animals gradually become 

 reciprocally adjusted so that a self-perpetuating condition of 

 practically stable equilibrium is established; in other words, what 

 is termed a 'balanced aquarium.' The rise and fall of teeming 

 populations, made possible by the rapidly changing environmental 

 conditions which the bringing together of hay and water initiated, 

 is replaced by an apparently harmonious interdependence of or- 

 ganisms demanding different food conditions, such as we are 

 familiar with in the world at large. 



