Support for the militarist estimate of the strength of the fighting emotions and instincts--Growing opposition to the fighting emotions and instincts as displayed in war--The desirability of preserving the martial virtues--Moral substitutes for warfare--Physical substitutes for warfare--The significance of international athletic competitions 285-301 A LIST OF PUBLISHED RESEARCHES FROM THE PHYSIOLOGICAL LABORATORY IN HARVARD UNIVERSITY 302-303 INDEX 305 LIST OF ILLUSTRATIONS Figure Page 1. Diagram of the more important distributions of the autonomic nervous system 25 2. Diagram of the arrangements for recording contractions of the intestinal muscle 49 3. Intestinal muscle beating in inactive blood 53 4. Alternate application of “excited” blood and “quiet” blood, from the same animal, to intestinal muscle initially beating in Ringer’s solution 55 5. The effect of prolonging the excitement 55 6. Failure of the cava blood to produce inhibition when excitement has occurred after removal of the adrenal glands 57 7. Effect of adding adrenin to formerly inactive blood 58 8. The effect of bubbling oxygen through active blood 59 9. Intestinal muscle beating in normal vena cava blood 62 10. The shielded electrodes used in stimulating the splanchnic nerves 87 11. Contraction of the _tibialis anticus_ and stimulation of the left splanchnic nerves 89 12. Arterial blood pressure with membrane manometer, contractions of _tibialis anticus_, and splanchnic stimulation 91 13-17. Effect of varying arterial blood pressure upon muscular contraction over time 98-104 18. Threshold stimulus of muscles during an experiment 116 19. Threshold stimulus of muscles during an experiment 122 20. Threshold stimulus of muscles during an experiment 124 21. Effect of adrenin injection upon blood pressure and contractions of the _tibialis anticus_ muscle 128 22. Effect of amyl nitrite injection upon blood pressure and contractions of the _tibialis anticus_ muscle 128