The Glands of Combat, the glands of emergency energy, the glands of preparedness,--such are the adrenal glands when viewed from the adrenalin standpoint. A picture of its activity in the evolutionary scheme of struggle and survival is something like the following: meeting an enemy, the animal is put in danger. It must fight or flee for its life. In either case, certain conditions must be fulfilled, if the body of the animal endangered is to be saved. To prevent injury to itself, and to do as much injury as possible to the foe--that becomes its immediate urge and necessity. Of the two animals, if in one the heart should begin to beat more strongly, the blood pressure to rise, the blood to flow more rapidly through the attacking instruments, the muscles, the teeth and claws, the brain and its eyes, while the other animal experiences none of these, the former will be the victor in fight or flight. Adrenalin may be looked upon as the invention for the mobilization at a moment's notice, or as we say, after generations of use, by instinct, of all these visceral and blood advantages in the struggle of combat or flight. The nature of instinct, in its relation to the glands of internal secretion, is a problem for another chapter. But we may note that the James-Lange theory of an emotion regards it as a consciousness of the very changes in the organism adrenalin causes. Since adrenalin is the starter of the whole process, and since McDougal has defined emotion as the feeling aspect of an instinct, just as an instinct may be defined as the motor aspect of an emotion, the adrenals as emotion-genetic, and instinct-genetic, play a part in the most profound processes of the subconscious and unconscious. THE MECHANISM OF FEAR