382 HUMAN PHYSIOLOGY 



physiology has interpreted the reaction for us from the 

 point of view of its value to the individual. 



'An emotional occasion is an occasion for action. This 

 was universally true under primitive conditions of life 

 among men and it is true in the lives of the lower animals. 

 Fear is the prelude to flight. Anger is the impulse to 

 attack. Under the experience of pain there are efforts to 

 escape from the cause of suffering where this is possible. 

 There is need for the fullest command of all bodily 

 resources in these crucial exigencies. It can be demon- 

 strated that adrenin helps to realize such a command. 



Take first the effect upon the distribution of the blood 

 noted above. It is clearly favorable to the maximum 

 activity of the muscles. The progress of digestion and 

 the other processes which may be going on in the ab- 

 dominal organs can be held in abeyance for the time 

 being. The most vital needs are given the precedence. 

 At the same time there is likely to be some rise of arterial 

 pressure and this accelerates the circulation through the 

 muscles. Until the actual struggle is under way the 

 skin may be pale rather than flushed; this indicates the 

 greatest possible concentration of the blood-flow in the 

 vessels of the motor organs. 



Another service of adrenin is known to be a postpone- 

 ment of fatigue. A very small addition of the adrenal 

 principle to the blood of an animal whose strength is 

 flagging may give a renewed command of the muscles. 

 The gain is partly in the way of better end-plate trans- 

 mission, but probably there are other points of applica- 

 tion. It is now believed that the secret of "the strength 

 of desperation" is largely in the timely discharge of 

 adrenin into the blood-stream. 



Still another result of the emotional disturbance is a 

 rapid transformation of the liver glycogen into sugar 

 which at once enters the blood. In Chapter XXIII it 

 has been stated that the resulting hyperglycemia may be 

 so marked as to cause the appearance of sugar in the 

 urine. The loss of the carbohydrate cannot be of any 



