We may conclude, therefore, that since the conditions of Wilenko’s observations are not comparable with emotional conditions, his inferences are not pertinent to the present discussion; that when both adrenin and sugar are increased in the blood as a result of excitement, the higher percentage of sugar is not due to adrenin inhibiting the use of sugar by the tissues, and that there is no evidence at present to show that the brief augmentation of adrenal discharge, following excitement or splanchnic stimulation, affects in any deleterious manner the utilization of sugar as a source of energy. Indeed, the observation of Wilenko and of Patterson and Starling, above mentioned, that adrenin increases the use of sugar by the heart, may signify that a _physiological_ discharge of the adrenals can have a favorable rather than an unfavorable effect on the employment of sugar by the tissues. The Vascular Changes Produced by Adrenin Favorable to Supreme Muscular Exertion Quite in harmony with the foregoing argument that sugar and adrenin, which are poured into the blood during emotional excitement, render the organism more efficient in the physical struggle for existence, are the vascular changes wrought by increased adrenin, probably in coöperation with sympathetic innervations. The studies of volume changes of parts of the body, made by Oliver and Schäfer, have already been mentioned. Their observations, it will be remembered, showed that injected adrenin drove the blood from the abdominal viscera into the organs called upon in emergencies--into the central nervous system, the lungs, the heart, and the active skeletal muscles. The absence of effective vasoconstrictor nerves in the brain and the lungs, and the dilation of vessels in the heart and skeletal muscles during times of increased activity, make the blood supply to these parts dependent on the height of general arterial pressure. In pain and great excitement, as we have already noted, this pressure is likely to be much elevated, and consequently the blood flow through the unconstricted or actually dilated vessels of the body will be all the more abundant.