Stannius ligature

Stannius Ligature is an experimental procedure to illustrate impulse conduction in frog heart. A ligature placed either around the junction between the sinus venosus and atrium of the frog or turtle heart (first stannius ligature) or around the atrioventricular junction (second stannius ligature); demonstrates that the cardiac impulse is conducted from sinus venosus to atria to ventricle, but that successive chambers possess automaticity since each may continue to beat, but the atria now have a slower rate than the sinus venosus, and the ventricle either does not contract or beats at a slower rate than the atria.