186. The Canon-forms differ from the foregoing classes of polyphonic composition in two respects: (1) The Imitation is entirely, or nearly, strict (par. 26); and (2) it is continuous; that is, not limited, as in the Fugue, to the Subject alone, but extended to include all that follows in the same voice, to the end of the Section, or Part, or entire composition.
187. a. The part which begins, or leads the canonic progression, is called the Leader (proposta); the following or imitating part is called the Follower, or responding part (risposta).
b. The principal distinction between canonic species (among many) is defined, precisely like the stretto, according to the distance of the Follower from the Leader in time, and in melodic interval; for instance, “Canon in the 8ve (or 2nd, 3rd, etc.) after one measure (or two, or more).”
c. Another important distinction is made between the Unaccompanied (or Independent) and Accompanied Canon; and further, between the Round and the Progressive Canon. Other traditional distinctions will either be defined in the following pages, or will be intentionally omitted because of their doubtful utility; for the latter the curious student may consult Dr. Baker’s “Dictionary of Musical Terms,” or Grove’s “Dictionary.”