The First Breath
When a baby is born, it must suddenly change its system of obtaining oxygen and disposing of carbon dioxide. Recent studies have revealed new details of what takes place during this critical episode of life
Volume 209, Issue 4
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Features
The Conservation Laws of Physics
Modern physics rests largely on classical laws of the constancy of such quantities as electric charge. The extension of physics into new realms, however, requires that these laws be re-examined
Foreign Nucleic Acids
In 1957 it was found that the cell defends itself against viruses with a protein called interferon. It now seems that this substance protects the cell against all the nucleic acids other than its own
Chondrites and Chondrules
The first are stony meteorites; the second, the small spherical bodies they contain. There is evidence that the chondrules date back to the opening stages in the evolution of the solar system
Afterimages
Recent experiments have elucidated the mechanism of these curious visual phenomena and have provided several new insights into the photochemistry of normal human vision
The Capital of the Nabataeans
Excavations at ancient Petra in the Middle East indicate something of the process by which a nomadic Arabian tribe became settled and Hellenized over a period of centuries
The Control of Growth in Plant Cells
Experiments showing that a new carrot plant can be produced from ordinarily nongrowing cells of the root provide clues about what causes and inhibits growth in living organisms
Place-Learning
When an animal learns to run a maze, has it learned a sequence of movements or some kind of map? This problem, which bears on the theory of learning, has occupied psychologists for 50 years