Read the passage from Sugar Changed the World . The end of slavery was a great step for human rights. But what did it mean on the sugar plantations—which had depended on extremely cheap labor to keep up with the twenty-four-hour cycle from harvest to mill? In 1836, the same John Gladstone whose sugar estate had exhibited the chained body of the slave leader Quamina wrote to a shipping company. Gladstone asked it to provide a hundred workers (the slang name was "coolies") from India to labor on his plantations. Gladstone's first ships, the Whitby , carrying 249 passengers, and the Hesperus , carrying 244, sailed for Demerara in 1838. What evidence do the authors include to support the central idea that the sugar plantations' cheap labor source changed from enslaved people to indentured Indians?