Interest in the field of ecology, which is centered in the developed countries, has recently increased due to the sudden discovery of a possible imbalance between man and earth. Resulting from the population explosion and the misuse of existing and newly developed technologies, this potential imbalance could bring about an environmental crisis menacing the future of mankind. In several countries the emergence of an interest in ecological problems has not been confined to the realm of the scientific community. It has aroused public concern which has expressed itself, although sometimes vaguely, in such initiatives as Earth Week, celebrated in the United States in April 1970, and the mushrooming of a specialized literature.