In the chapter entitled ‘Des huict Tons de l'Église’ (pp. 84–7), Denis turns his attention to certain problems related to the use of the organ in Gallican rite. These difficulties arose out of the practice of alternation between organ and choir during parts of the liturgy, a convention by then well established in France. The organ's interpolated sections, called versets, replaced sung plainsong portions of the Mass ordinary and proper, psalms, canticles, and hymns.

The first documentary evidence of ecclesiastical permission for alternation in France dates from 1510, although there are indications that alternatim practices of various kinds had become customary long before that. The first French keyboard versets to appear in print were contained in two volumes issued in 1530 and 1531 in Paris by Pierre Attaingnant, the Magnificat sur les huit tons avec Te deum laudamus et deux preludes and the Tablature pour le jeu dorgues espinetes et manicordions sur le plain chant de Cunctipotens et Kyrie fons. The versets in the Attaingnant volumes are characterized by technical simplicity and close correspondence to the plainsong melodies.

After the Attaingnant prints, there followed a gap of more than ninety years until the appearance of the next surviving printed collections of organ versets, the Hymnes de l'Eglise pour toucher sur l'orgue, avec les fugues et recherches sur leur plain-chant (Paris: Pierre Ballard, 1623) and Le Magnificat, ou cantique de la Vierge pour toucher sur l'orgue, suivant les huit tons de l'Eglise (Paris: Pierre Ballard, 1626) of Jehan Titelouze.