Fig. 2. Length/tension diagram for the m. hyoglossus of an adult Pogona vitticeps. In these experiments, the tongue of the lizard was attached to a force lever, its length was changed, the muscle was tetanically stimulated and the forces were recorded. The length/tension diagram for P. vitticeps is similar to that reported for other animals with typical cross-striated muscle, showing a rapid increase in tension, a distinct optimal length for contraction and a decrease in tension if the muscle is extended beyond its optimal length.