Scientific American Magazine

Pain is not a fixed response to a hurtful stimulus. Its perception is modified by our past experiences, our expectations and, more subtly, by our culture

Most galaxies are spiral, spherical or ellipsoidal aggregations of stars, but some have irregular configurations. These unusual objects may very well be galaxies in an early stage of evolution

These minute disks of protoplasm circulate in the bloodstream along with red and white cells. When a blood vessel is broken, platelets plug the break. They also play a key role in the formation of clots

The atom-by-atom structural formulas of three proteins have now been worked out. This knowledge should help in understanding how the structures of proteins are related to their biological activity

An account of Soviet work on the use of scale models to visualize tectonic processes. Because rigidity must be scaled down with time and space, rocks are represented by such materials as clay and syrup

In a wide variety of organisms from both the plant and animal kingdoms these tiny hairlike projections have the same basic structural plan: two long filaments surrounded by nine others

In the late 16th century a Danish nobleman built on the island of Hven the most ambitious astronomical observatory the world had yet seen. Its precise instruments created modern astronomy

Otherwise known as the shipworm, this distant relative of the clam destroys submerged wood by honeycombing it with burrows. Its way of life is predicated on its unusual ability to digest cellulose