[58] v. Kries: Studien zur Pulslehre, p. 62, and M. v. Frey, Die Untersuchung des Pulses, p. 164.
[59] Grashey: Die Wellenbewegung elastischer Röhren, p. 166, 1881.
[60] Hoorweg: Archiv f. d. ges. Physiologie, vol. 46, p. 143, 1890.
[61] Marey, loc. cit., pp. 267-271, and Traité de Physique Biologique (publié par d'Arsonval, Chauveau, Gariel, Marey), vol. 1, p. 390, 1901; these tracings are reproduced rather frequently; e.g., Pfungen, loc. cit., p. 563, and Chapman: Human Physiology (2d ed.), p. 270, 1899.
[62] E. Mach: Sitzungsberichte der K. Akademie der Wissenschaften, vol. 47 (2), p. 43, 1863; and in the tables, figs. 48-53.
[63] L. Hill, in Schaefer's Text-book of Physiology, vol. 2, p. 111, 1902. The same opinion maybe found in Hermann's Lehrbuch der Physiologie (12th ed.), p. 79, 1900. "Ihre (der dicrotischen Wellen) Erklärung ist noch nicht widerspruchsfrei gestellt." In the previous editions different views were given, and this critical doubt may be regarded as the final outcome of the investigations of almost half a century.
[64] Sudden compression is the most convenient way of producing a wave in a liquid which is enclosed in an elastic tube. It was used already in the first experiments on the propagation of these waves. (E. H. Weber: Anwendung der Wellenlehre auf die Lehre vom Kreislaufe des Blutes und insbesondere auf die Pulslehre, Berichte d. Kgl. Sächsischen Ges. d. Wissenschaften, Math.-Phys. Cl., p. 177, 1850.)
[65] Bayliss and Starling: On the form of the intraventricular and aortic pressure curves obtained by a new method, Intern. Monatsschrift f. Anatomie u. Physiologie, vol. 11, pp. 426-435, 1894.
[66] W. T. Porter: A new method for the study of the intraventricular pressure curve, Journal of Experimental Medicine, vol. 1, pp. 296-303, 1896. A similar method was used by O. Frank: Ein experimentelles Hülfsmittel für die Kritik der Kammerdruckkurven, Zeitschrift f. Biologie, vol. 35, pp. 478-480, 1897.
[67] O. Frank, loc. cit., p. 480.