WHAT constitutes living? There are many and varied defi- nitions, but from the standpoint of the technologist, living is a term used to describe the functioning of any organism on the area in which it exists. Let us view living, then, in terms of function. All organic mechanisms require food, water, air and solar radiation in some form or other. They are capable of motion, various metabolic changes, and reproduction. The hu- man mechanism is differentiated functionally from all others in that it is the only one of the entire series capable of producing energy-consuming devices outside of its organic entity. The history of the human race may well be stated in terms of the ability of man to consume ever-increasing amounts of extran- eous (non-human) energy. The limitation and stabilization of that rate of increase is the scientific problem of the not far distant future.