Answer: I thiiiiiinnnk the answer would be the first quote: “They are Nature’s watchmen,— links which connect the days of animated life.”
Explanation: The reason I think this is because we are talking about how he feels about the “natural world.” My guess came from the fact that he views the animals as “Nature’s watchmen,” and feels that they are the “links which connect the days of animated life.”
I deeply apologize if this is incorrect. Good luck!