In case strong emotions are followed by vigorous exertions, therefore, asphyxia is likely to result, and this will act in conjunction with the emotional excitement and pain, or perhaps in continuation of the influences of these states, to bring forth still more adrenal discharge and still further output of sugar from the liver. And these in turn would serve the laboring muscles in the manner already described. This suggestion is in accord with Macleod’s[156] that the increased freeing of glycogen from the liver produced by muscular exercise is possibly associated with increased carbon-dioxide in the blood. And it also harmonizes with Zuntz’s statement[157] that the asphyxia of great physical exertion may call out sugar to such a degree that, in spite of the increased use of it in the active muscles, glycosuria may ensue. The evidence previously adduced that adrenin causes relaxation of the smooth muscle of the bronchioles, taken in conjunction with the evidence that adrenal secretion is liberated in asphyxia, suggests that relief from difficult breathing may thus be automatically provided for in the organism. The well-known phenomenon of “second wind” is characterized by an almost miraculous refreshment and renewal of vigor, after an individual has persisted in violent exertion in spite of being “out of breath.” It seems not improbable that this phenomenon, for which many explanations have been offered, is really due to setting in operation the supporting mechanism which, as we have seen, plays so important a rôle in augmenting bodily vigor in emotional excitement. The release of sugar and adrenin, the abundance of blood flow through the muscles--supplying energy and lessening fatigue--and the relaxation of the bronchiolar walls, are all occurrences which may reasonably be regarded as resulting from asphyxia. And when they take place they doubtless do much to abolish the distress itself by which they were occasioned. According to this explanation “second wind” would consist in the establishment of the same group of bodily changes, leading to more efficient physical struggle, that are observed in pain and excitement. The Utility of Rapid Coagulation in Preventing Loss of Blood