Originally published in 1938, this book explores the problem of the adjustment of the population in the early 20^th century to the agricultural-economic environment in a geographical and economic setting. The study of the modern problem of population growth is also one of human adjustment in its wider sense to the whole of the environment, which in itself is an ensemble of various interdependent factors. The study is based on a classification of agricultural regions in the Ganges Valley which shows some of the world's highest records of agricultural productivity.