If you look back at the preface of the poem, you'll see that the writer left out several words from the quoted material that she felt added nothing to her discussion. When we do that we indicate the gap with an ellipsis -- three spaced dots. If a sentence-ending period had appeared somewhere within that gap or if the ellipsis appeared at the end of one of our sentences, we would have four dots, one for the period and three for the ellipsis.