Fig. 2. Proportions of contractile elements (myosin ATPase; open columns), mitochondria (pale shaded columns) and sarcoplasmic reticulum (SR; dark shaded columns) in synchronous muscle (A), asynchronous muscle (B) and singing muscle (C) from insects. The frequencies noted reflect the typical contraction rates for flying or singing for the muscle illustrated. Data from Casey and Ellington (1989), Josephson and Young (1985) and Ready (1986).