Feature

Heavy Water Lowers Plant’s Food-Making Efficiency

Brief Treatment in Clinic Improves Mental Patients

Nature Ramblings: Crusty Convincers

Museums Lack Specimens of Animals Now Becoming Extinct

First Glances at New Books

Front Matter

Man-Made Gamma Rays Six Times as Piercing as Nature’s

Electrical Device Aids in Measuring Speeds of Cars

Find New Way to Attack Disease of Muscle Weakness

Sound Recording Methods Preserve Bird Calls

[Photographs]: Fossil Tree’s Structure

Italy’s Chemists Gave Her Weapons for War in 1934