In this excerpt. Justice Harlan is warning against

Allowing interstate commerce to be dominated by powerful monopolies.

Explanation:

Here's the complete question:

All who recall the condition of the country in 1890 will remember that . . . the country was in real danger from another kind of slavery . . . that would result from the aggregations of capital in the hands of a few individuals and (businesses) controlling, for their own profit and advantage exclusively, the entire business of the country, including the production and sale of the necessaries of life." —Supreme Court Justice John Marshall Harlan, 1911

In this excerpt, Justice Harlan is warning against —

John Marshall Harlan, was an associate justice of the Supreme Court of the United States from from 1877 till when he died in 1911.

In this excerpt, Justice Harlan is warning against allowing interstate commerce to be dominated by powerful monopolies.

He believes that when interstate commerce is left in the hands of few, powerful individuals, it is a form of slavery as the businesses will only look to extort the people and make more profit and do things that'll only be beneficial to them.

answer: a tolerated diverse population

explanation: the city of baghdad formed to vast semi- circles on the right and left banks of the tigris twelve miles in a diameter.