[Footnote 33: Zeitschrift für Biologie, 1912, lviii, p. 274.] [Footnote 34: Meltzer and Joseph: American Journal of Physiology, 1912, xxix, p. xxxiv.] [Footnote 35: Elliott: Journal of Physiology, 1912, xliv, p. 400.] [Footnote 36: Cannon and Lyman: American Journal of Physiology, 1913, xxxi, p. 377.] [Footnote 37: Elliott: Journal of Physiology, 1912, xliv, p. 400.] [Footnote 38: Folin, Cannon and Denis: Journal of Biological Chemistry, 1913, xiii, p. 477.] [Footnote 39: Fraenkel: Archiv für experimentelle Pathologie und Pharmakologie, 1909, lx, p. 399.] [Footnote 40: See O’Connor: Archiv für die experimentelle Pathologie und Pharmakologie, 1912, lxvii, p. 206.] [Footnote 41: Grutzner: Ergebnisse der Physiologie, 1904, iii², p. 66; Magnus: _Loc. cit._, p. 69.] [Footnote 42: Hoskins: Journal of Pharmacology and Experimental Therapeutics, 1911, iii, p. 95.] CHAPTER IV ADRENAL SECRETION IN STRONG EMOTIONS AND PAIN If the secretion of adrenin is increased in strong emotional states and in pain, that constitutes a fact of considerable significance, for, as already mentioned, adrenin is capable of producing many of the bodily changes which are characteristically manifested in emotional and painful experiences. It is a matter of prime importance for further discussion to determine whether the adrenal glands are in fact roused to special activity in times of stress. The Evidence that Adrenal Secretion Is Increased in Emotional Excitement That blood from the adrenal veins causes the relaxation of intestinal muscle characteristic of adrenal extract or adrenin is shown in Fig. 3. The muscle was originally beating in blood which contained no demonstrable amount of adrenal secretion; this inactive blood was replaced by blood from the adrenal veins, obtained after quick etherization. Etherization, it will be recalled, is accompanied by a “stage of excitement.” Relaxation occurred almost immediately (at _b_). Then the rhythm was renewed in the former blood, and thereupon the muscle was surrounded with blood from the vein leading away from the left kidney, i. e., blood obtained from the same animal and under the same conditions as the adrenal blood, but from a neighboring vein. No relaxation occurred. By this and other similar tests the reliability of the method was proved. [Illustration: Figure 3.--Intestinal muscle beating in inactive blood, which was withdrawn from the chamber at _a_. Blood from the _adrenal_ vein of an animal excited by etherization was substituted at _b_, and withdrawn at _c_. Contractions were restored in the original inactive blood which was removed at _d_. Blood from the _renal_ vein (same animal) was added at _e_. In this and subsequent records time is marked in half minutes.]