Fig. 1. Schematic diagram of cross sections of the tentacular stalk (A) and arm (B) of the squid Loligo pealei. The core of the tentacle and the arm consists of a densely packed mass of transverse muscle fibres (T) oriented perpendicular to the long axis of the appendages. The axial nerve cord (Ax) and longitudinal muscles (L) are also visible in the diagram. The muscle fibre bundle preparations (shaded) were obtained by cutting a small section from a transverse slice of the arm or tentacle. The foil clips used to hold the preparation in the testing apparatus were attached to the ends of the preparation (shaded and cross-hatched) in such a way that only transverse muscle fibres were present between the clips.