H. E. D. J. TER KEURS & M. I. M. NOBLE The "Starling's Law of the Heart" and "The Frank-Starling Mechanism" have long been the cornerstone of cardiac mechanical physiology. It is often forgotten that Frank and Starling carried out fundamentally different exper- iments. Frankl measured the isovolumic pressure developed by frog heart at different volumes. He therefore discovered the pressure-volume-volume rela- tionship which depends directly on the force-length relationship of the 2 sarcomeres. Starling ,3 studied cardiac shortening as manifest by cardiac output and its relationship to...