II. Photographic determination of the time-relations of the changes which take place in muscle during the period of so-called 'latent stimulation

It is now forty years since Helmholtz published his fundamental experiments on the time-relations of muscular contractions. The purpose of this investigation was to ascertain “the periods and stages in which the energy of muscle rises and sinks after instantaneous stimulation;” the word energy being defined as the “mechanical expression of activity;” and one of the most important conclusions of the author was that, in the muscles investigated by him, contraction does not begin until nearly one hundredth of a second after excitation. This interval has, by subsequent writers, been called the period of “latent stimulation.”