The evidence adduced in the last chapter indicated that the greater “head” of arterial pressure produced by the more rapid heart beat and the stronger contraction of many arterioles in times of great excitement would be highly serviceable to the organism in any extensive muscular activity which the excitement might involve. By assuring an abundant flow of blood through the enlarged vessels of the working muscle, the waste products resulting from the wear and tear in contraction would be promptly swept away and thus would be prevented from impairing the muscular efficiency. The adrenin discharge at such times would, as was pointed out, probably reënforce the effects of sympathetic impulses. The evidence presented in this chapter shows that adrenin has also another action, a very remarkable action, that of restoring to a muscle its original ability to respond to stimulation, after that has been largely lost by continued activity through a long period. What rest will do only after an hour or more, adrenin will do in five minutes or less. The bearing of this striking phenomenon on the functions of the organism in times of great need for muscular activity will be considered in a later discussion. REFERENCES [Footnote 85: Gruber: American Journal of Physiology, 1913, xxxii, p. 437.] [Footnote 86: E. L. Porter: American Journal of Physiology, 1912, xxxi, p. 149.] [Footnote 87: Cannon and Nice: American Journal of Physiology, 1913, xxxii, p. 55.] [Footnote 88: Albanese: Archives Italiennes de Biologie, 1892, xvii, p. 239.] [Footnote 89: Abelous and Langlois: Archives de Physiologie, 1892, xxiv, pp. 269-278, 465-476.] [Footnote 90: Radwánska: Anzeiger der Akademie, Krakau, 1910, pp. 728-736. Reviewed in the Centralblatt für Biochemie und Biophysik, 1911, xi, p. 467.] [Footnote 91: Panella: Archives Italiennes de Biologie, 1907, xlvii, p. 30.] [Footnote 92: Langley: Proceedings of the Royal Society of London, 1906, lxxviii, B, p. 181. Journal of Physiology, 1905-6, xxxiii, pp. 374-413.] [Footnote 93: See Gruber: American Journal of Physiology, 1914, xxxiv, p. 89.] CHAPTER IX THE HASTENING OF COAGULATION OF BLOOD BY ADRENIN