term, “digest’’ is to be distinguished from “abridgment.” The latter is a sumyoary or cpio of the contents of a single work, in which, as a rule, the original order or sequence of parts is preserved, and in which the principal labor of the compiler is in the matter of consolidation. A digest is wider in its scope; is made up of quotations or paraphrased passages; and has its own system 0 classification and arrangement. An “index” merely points out the places where particular matters may be found, without purporting tu give such matters tn extenso. A “‘treatise’ or “commentary” is not a compilation, but an original composition, though it may include quotations and excerpts.