This book differs from the other books in its central concern with statement about the future as made by a wide range of scientists. The subject areas covered are extensive and specialists in every field will find materials than can be improved and extended. This book is an effort to summarize the basic concept and principles of the subject to present the elementary factual information with which a person to be competent in the field should be familiar and to sow how these principles and facts may be applied in a practical way to the interests and welfare of man.