Answer: Tone in a piece of writing is created through the use of language, including word choice, sentence structure, and literary devices, to convey the writer's attitude or feelings towards the subject matter.
Explanation: The tone of this passage is admiring and reverential. The author speaks of the Calypso borealis as "the rarest and most beautiful of the flowering plants," and uses phrases such as "struggling through tangled drooping branches" and "flooded forests of the Orinoco described by Humboldt" to convey a sense of adventure and exploration. The use of terms such as "monkey's nest," "eagle's," or "Indian's" also implies a deep appreciation for the natural world and indigenous cultures.