Scientific American Magazine

An account of how physical theory has developed in the past and how, in the light of this development, it can perhaps be expected to develop in the future

They are produced when figures with periodic rulings are made to overlap. A study of their basic properties reveals that they can illuminate many problems of scientific interest

This small particle acts as the digestive tract of the living cell. Its enzymes dissolve the substances ingested by the cell and under certain circumstances can dissolve the cell itself

It has been five years since these rings of trapped particles were discovered. Presenting a review of present knowledge of the belts, with special reference to particles injected by nuclear explosions

A pheromone is a substance secreted by an animal that influences the behavior of other animals of the same species. Recent studies indicate that such chemical communication is surprisingly common

A rich assemblage of obsidian tools has been discovered at El Inga, high in the mountains of Ecuador. It may provide a Long-sought link between the prehistoric men of the U.S. and those of South America

A basic human attribute that has long resisted investigation can now be measured with the help of a simple device. The key to the measured with is what happens when the subject is given a short rest

This prolific fish has been introduced into many less developed areas as a cheap source of protein-rich human food. A new method for making it grow larger in ponds may enhance its usefulness