sections vary from two to 25 seconds, and each is given a rehearsal number. In some sections of the work, the temporal processes within the sonoristic system become complex, with multiple entrances in several instrumental parts. To clarify his intentions, these sections are divided into seconds, with vertical lines in the score marking off each second. In Polymorphia, this occurs from rehearsals 11–24, 33–37, and 57–59. Pitch notation Penderecki uses a staff in the notation of his sonoristic scores in places where a point of reference as to pitch is necessary. Generally, precision of pitch is of secondary importance in his sonoristic pieces. For instance, his use of quarter tones is not necessarily because a quarter-tone scale exists in his work, but they “are employed merely to regulate precisely the internal structure of a cluster, that is, to give clusters the desired density.” This technique is used extensively in both A sections of the work which are dominated by sustained pitch clusters. Additionally, from rehearsal number 11 through two-and-a-half seconds after rehearsal 24, he uses a staff with a starting pitch and then a line representing the tessitura of the material to be performed, rather than using the traditional notation. This technique makes possible the proper communication of details of this highly complex passage of clusters in Polymorphia. Graphic symbols Penderecki communicates many of his timbral effects via means much more pictorial than in traditional Western music notation. These effects and their system of notation represent a key element of his style during this first compositional period. It is essentially a more advanced version of the system used in the Threnody for the Victims of Hiroshima, and it is further developed in the 1962 work Fluorescences. The score includes a page explaining 21 abbreviations and symbols which he uses throughout. A black triangle indicates that one should play “the highest note of instrument (indefinite pitch) ”. This effect occurs throughout the work and, as with the quarter tone effects mentioned above, the precise pitch of the note is not critical to the composition. Thus, Penderecki notates it without the staff, helping to make his notational system as visually efficient as possible. Another effect instructs the performer to “tap the desk with the bow or the chair with the heel.” Here, Penderecki turns traditionally non-musical items into instruments which are included in the work. This technique is used primarily in the