Read it through once

Flocks of black women passed along, carrying outrageously heavy bags of freight on their heads. The quiver of their leg as the foot was planted and the strain exhibited by their bodies showed what a tax upon their strength the load was. They were stevedores and doing full stevedore's work. They were very erect when unladden—from carrying weights on their heads—just like the Indian women. It gives them a proud fine carriage.