Q. In the example at CMOS 13.53, why is it a period at the end instead of “. . . .”? It’s not the end of the sentence in the original quote, and the period seems to suggest there is nothing further in that sentence with the single period.
A. Although it might be logical to put an ellipsis at the end, that’s not the convention. Quotations are nearly always, by their very nature, excerpted from a longer sentence, paragraph, or document. There’s no need to indicate that with special punctuation. Please see CMOS 13.52: “Ellipsis points are normally not used (1) before the first word of a quotation, even if the beginning of the original sentence has been omitted; or (2) after the last word of a quotation, even if the end of the original sentence has been omitted, unless the sentence as quoted is deliberately incomplete.”