A fascinating scientific classic from 1911 exploring the ancient world of fermented milk, probiotic bacteria, and the secrets of human longevity.

In The Bacillus of Long Life, pioneering researcher Loudon M. Douglas investigates the remarkable traditions of yoghurt, keffir, koumiss, leben, matzoon, and other fermented milks consumed for centuries across Bulgaria, the Caucasus, Armenia, Arabia, India, and Eastern Europe.

Blending history, microbiology, chemistry, anthropology, and early nutritional science, Douglas examines why certain rural populations famed for exceptional longevity relied heavily on soured milk as a daily food. Drawing upon the revolutionary bacteriological discoveries of Louis Pasteur and Élie Metchnikoff, the book became one of the earliest popular works to explore the relationship between beneficial bacteria, digestion, and healthy aging.

Inside this richly detailed volume readers will discover:

• The ancient origins of fermented milk across Europe, Asia, and Africa
• Traditional preparation methods for yoghurt, kefir, koumiss, leben, and matzoon
• Early scientific studies of lactic acid bacteria and gut health
• Historical accounts of Bulgarian and Balkan centenarians
• The chemistry and bacteriology of milk fermentation
• Edwardian medical theories surrounding longevity and digestion
• Traditional dairy practices from Bedouin tribes, Armenian villages, and Central Asian nomads
• Rare insights into pre-modern nutritional science and probiotic foods

Part scientific handbook, part historical travelogue, and part medical curiosity, The Bacillus of Long Life captures a pivotal moment when ancient dietary traditions met the emerging science of microbiology.

This restored edition preserves the charm and intellectual curiosity of the original 1911 publication while presenting the text in a modern digital format optimized for today’s readers.

Ideal for readers interested in:

Probiotic history
Fermented foods
Nutrition science
Dairy history
Longevity research
Medical history
Historical microbiology
Traditional food cultures
Early twentieth-century science

A remarkable journey into the forgotten origins of modern probiotic culture and humanity’s timeless search for long life.