Ch.2 Marlow and the cannibals

In ch.2, Marlow has a bizzare moment of imagining himself through the eyes of the cannibals he's with. From "Why in the name of all the...." to this paragraph's end, ".....behind the blind whiteness of the fog," I've been told that the language spoken in this passage can be viewed both as at times explicitly racist and at other times more ambiguous. I am to analyze the language of this passage, but I'm already stuck on thesis statement... The significance of the passage, I guess, has to do with the racist and ambiguous ways Marlow speaks, but I don't get how the way he speaks sounds "racist" but then "ambiguous" as well.
If anyone can point out how these two words work in this passage and give rise to its significance, I would really appreciate your help.:thumbs_up