Images of jungle fauna (animal life) and flora (plant life) permeate much of the poem, from “barbaric birds” (Line 13) and “jungle herds” (Line 14) in the second stanza to “silver snakes” (Line 41) and “leprous flowers” (Line 46) in the third. In their freedom and their wildness, these serve as contrast to the speaker’s tamed, civilized life in America. The images seem to both appeal to and appall the speaker. The freedom and wildness of the jungle imply aggression and danger: Huge animals trample the grass (Lines 15-16), fierce cats stalk and kill their prey (Lines 34-40), and beautiful flowers could turn out to be poisonous. Perhaps even “savage measures” (Line 50), or untamed passions, of “[j]ungle boys and girls in love” (Line 51) imply potential violence. That explains the speaker’s reaction: “I cram against my ear / Both my thumbs, and keep them there” (Lines 20-21). These symbols of pre-civilized wildness evoke the possibility of the speaker betraying their habits of civilized behavior if they allow their grief and anger to get the best of them.