How does Nathan Irvin Huggins use imagery in Voices from the Harlem Renaissance?

Imagery:

"The tide of Negro migration, northward and city-ward, is not to be fully explained as a blind flood started by the demands of war industry coupled with the shutting off of foreign migration, or by the pressure of poor crops coupled with increased social terrorism in certain sections of the South and Southwest. Neither labor demand, the boll weevil nor the Ku Klux Klan is a basic factor, however contributory any or all of them may have been."

"For, as the whites have their blonde and brunette, so do the blacks have their chocolate, chocolate-to-the-bone, brown, low-brown, teasing-brown, high-brown, yellow, high-yellow and so on. The difference on our side is so much more interesting and funny."