Feature

New Machine Gun Able to Change Rate while Firing

Traces Invasion Route of Infantile Paralysis Virus

America Builds Food Defense

Recovered Patient Re-Lives Experience in Sanitarium

Challenge Price Boosts, Is Advice to Consumers

First Glances at New Books

Critical Tests Made on Sulfapyridine for Cows

Swine Erysipelas May Infect Human Beings

In Science Fields

Mosquitoes Kept Suppressed on South’s Eight New Lakes

Front Matter

Green Plants Give off Faint Red Radiation